Safe medication administration is a vital component of the nursing role. Each day it is common for nurses to make clinical judgments regarding the safety, appropriateness, and effectiveness of the medications administered to their clients.

Examples of decisions that a nurse might make during client care include:

• Is my client’s heart rate within the correct range to receive this beta-blocker medication?
• Does my client have adequate renal function prior to administering this dose of antibiotic?
• Is this pain medication effective in controlling my client’s discomfort?

In order to make safe medication administration decisions, the nurse must have a strong understanding of pharmacology. Symptom management, physical recovery, and individual well-being can be strongly connected to the use of medications in a client’s treatment plan. Before a nurse reviews a medication order, checks a medication administration record, or administers a medication, it is important to have a foundational understanding of how medications work within the human body.

Nurses should understand the key components of pharmacology

• Pharmacotherapeutics: The clinical purpose or reason for the medication
• Pharmacokinetics: The movement of the drug through the body
• Pharmacodynamics: The physiological response of the body to the drug.

These next sections will introduce pharmacokinetics and pharmacodynamics. Future chapters of this textbook will focus on the pharmacotherapeutics of specific drug classifications.

Pharmacokinetics

Pharmacokinetics is the term that describes the four stages of absorption, distribution, metabolism, and excretion of drugs. Drugs are medications or other substances that have a physiological effect when introduced to the body. There are four basic stages for a medication to go through within the human body: absorption, distribution, metabolism, and excretion. This entire process is sometimes abbreviated ADME. Absorption occurs after medications enter the body and travel from the site of administration into the body’s circulation. Distribution is the process by which medication is distributed throughout the body. Metabolism is the breakdown of a drug molecule. Excretion is the process by which the body eliminates waste. Each of these stages is described separately later in this chapter.

Research scientists who specialize in pharmacokinetics must also pay attention to another dimension of drug action within the body: time. Unfortunately, scientists do not have the ability to actually see where a drug is going or how long it is active. To compensate, they use mathematical models and precise measurements of blood and urine to determine where a drug goes and how much of the drug (or breakdown product) remains after the body processes it. Other indicators, such as blood levels of liver enzymes, can help predict how much of a drug is going to be absorbed.

Principles of chemistry are also applied while studying pharmacokinetics because the interactions between drug and body molecules are really just a series of chemical reactions. Understanding the chemical encounters between drugs and biological environments, such as the bloodstream and the oily surfaces of cells, is necessary to predict how much of a drug will be metabolized by the body.

Pharmacodynamics

Pharmacodynamics refers to the effects of drugs in the body and the mechanism of their action. As a drug travels through the bloodstream, it will exhibit a unique affinity for the drug-receptor site, meaning how strongly it will bind to the site. Other components of pharmacodynamics include ion channels, enzymes, and the immune system.

Examination of the ways in which drugs and receptor sites create a lock and key system (see Figure 1.2a) is helpful to understand how drugs work and the amount of drug that may be left circulating within the bloodstream. This concept is broadly termed as drug bioavailability. The bioavailability of drugs is an important feature that chemists and pharmaceutical scientists keep in mind when designing and packaging medicines.

Figure 1.2a Pharmacodynamics: Drug and Receptor Binding

The Relationship Between Pharmacokinetics and Pharmacodynamics

Essentially, pharmacokinetics is the movement of drugs through the body, and pharmacodynamics is the body’s biological response to the drugs. Pharmacokinetics and pharmacodynamics need to be considered when administering medications. Figure 1.2b displays the relationship between pharmacokinetics and pharmacodynamics.

Figure 1.2b The Relationship Between Pharmacokinetics and Pharmacodynamics. [Image Description]

Pharmacogenetics

No matter how effectively a drug works in a laboratory simulation, the performance in the human body will not always produce exactly the same results, and individualized responses to drugs have to be considered. Although many responses to medications may be anticipated, one’s unique genetic makeup may also have a significant impact on one’s response to a drug. Pharmacogenetics is defined as the study of how people’s genes affect their response to medicines..

Image Description

Figure 1.2b image description:

1. Pharmacokinetics
   1. Absorption
   2. Distribution
   3. Metabolism
   4. Excretion
2. Pharmacodynamics
   1. Receptors
   2. Ion Channels
   3. Enzymes
   4. Immune System
3. Physiological Response [Return to Figure 1.2b]

The first stage of pharmacokinetics is known as absorption. Absorption occurs after drugs enter the body and travel from the site of administration into the body’s circulation. Medications can enter the body through various routes of administration. Common routes to administer medications include the following examples:

• oral (swallowing an aspirin tablet)
• sublingual (dissolved under the tongue)
• enteral (administering to the GI tract such as via a nasogastric tube)
• rectal (administering a Tylenol suppository)
• inhalation (breathing in medication from an inhaler)
• intramuscular (getting a flu shot in the deltoid muscle)
• subcutaneous (injecting insulin into the fat tissue beneath the skin)
• transdermal (wearing a nicotine patch)

When a medication is administered orally or enterally, it faces its biggest hurdle during absorption in the gastrointestinal (GI) tract. Medications made of protein, that are swallowed or otherwise absorbed in the GI tract, may quickly be deactivated by enzymes as they pass through the stomach and duodenum. If the drug does get into the blood from the intestines, part of it will be broken down by liver enzymes, known as the first-pass effect, and some of it will escape to the general circulation to either become protein-bound (inactive) or stay free (and create an action at a receptor site). These metabolic effects are further described in the “Metabolism” section later in this chapter. Providers who prescribe medications, as well as nurses, understand that several doses of an oral medication may be needed before enough free drug stays active in the circulation to exert the desired effect.

A workaround to the first-pass effect is to administer the medication using alternate routes such as dermal, nasal,  inhalation, injection, or intravenous. Alternative routes of medication administration bypass the first-pass effect by entering the bloodstream directly or via absorption through the skin or lungs. Medications that are administered directly into the bloodstream (referred to as intravenous medications) do not undergo absorption and are fully available for distribution to tissues within the body.

Alternative routes of medication have other potential problems to consider. For example, injections are often painful and cause a break in the skin, an important barrier to infection. They can also be costly and difficult to administer daily, cause localized side effects, or contribute to unpredictable fluctuations in medication blood levels.

Figure 1.3a Applying Transdermal Patch

Transdermal application of medication is an alternate route that has the primary benefit of slow, steady drug delivery directly to the bloodstream—without passing through the liver first.  (See Figure 1.3a for an image of applying a transdermal patch.) Drugs delivered transdermally enter the blood via a meshwork of small arteries, veins, and capillaries in the skin. This makes the transdermal route of drug delivery particularly useful when medication must be administered over a long period of time to control symptoms. For example, transdermal application of fentanyl, a pain medication, can provide effective pain management over a long period of time; the scopolamine patch can control motion sickness over the duration of a cruise ship vacation, and the nitroglycerin patch is used to control chronic chest pain. Despite their advantages, skin patches have a significant drawback in that only very small drug molecules can enter the body through the skin, making this application route not applicable for all types of medications.

Inhaling drugs through the nose or mouth is another alternative route for rapid medication delivery that bypasses the liver (see Figure 1.3b). Metered-dose inhalers have been a mainstay of asthma therapy for several years, and nasal steroid medications are often prescribed for allergy and sinus problems.

Lifespan Considerations

Neonate & Pediatric: Gastric absorption in neonatal and pediatric clients varies from that of their adult counterparts. In neonate and pediatric clients, the acid-producing cells of the stomach are immature until around the age of one to two years. Additionally, gastric emptying may be decreased because of slowed or irregular peristalsis (forward bowel movement). The liver of a neonatal or pediatric client continues to mature, experiencing a decrease in first-pass elimination, resulting in higher drug levels in the bloodstream.

Older Adult:  As a natural result of aging, older adults will experience decreased blood flow to tissues within the GI tract. In addition, there may be changes in the gastric (stomach) pH that may alter the absorption of certain medications. Older adult clients may also experience variations in available plasma proteins, which can impact drug levels of medications that are highly protein-bound. Consideration must also be given to the use of subcutaneous and intramuscular injections in older clients experiencing decreased cardiac output. Decreased drug absorption of medications can occur when peripheral circulation is decreased. Finally, as adults age, they often have less body fat, resulting in decreased absorption of medication from transdermal patches that require adequate subcutaneous fat stores for proper absorption.Table 1 summarizes route options that a nurse should consider when administering medication.

Attributions

• “Table 1.3: Medication Route Considerations” was adapted from Chapter 1.3 Pharmacokinetics in Principles of Pharmacology by Carl Rosow, David Standaert, and Gary Strichartz, which is licenced under a CC BY-NC-SA 4.0 licence. Adapted by Amanda Egert, Kimberly Lee, and Manu Gill.

The second stage of pharmacokinetics is the process known as drug distribution. Distribution is the process by which medication is dispersed throughout the body via the bloodstream. Once a drug enters into systemic circulation by absorption or direct administration, it must be distributed into interstitial and intracellular fluids to get to the target cells. The distribution of a drug throughout the body is dependent on common factors such as blood flow, plasma protein binding, lipid solubility, the blood-brain barrier, and the placental barrier. Other factors include capillary permeability, differences between blood/tissue, and volume of distribution.

Distribution of a medication can also cause unintended adverse effects or side effects. Drugs are designed to primarily cause one effect, meaning they bind more strongly to one specific receptor site and predictably cause or block an action.  However, side effects can occur when the drug binds to other sites in addition to the target tissue, causing secondary side effects.  These side effects can range from tolerable to unacceptable resulting in the discontinuation of the medication. For example, a person might take the pain reliever ibuprofen (Advil) to treat a sore leg muscle, and the pain may be subsequently relieved, but there may also be stomach irritation as a side effect that may cause the person to stop taking Ibuprofen.

Blood Flow

The blood stream carries medications to their destinations in the body.  Many factors can affect the blood flow and delivery of medication, such as decreased flow (due to dehydration), blocked vessels (due to atherosclerosis), constricted vessels (due to uncontrolled hypertension), or weakened pumping by the heart muscle (due to heart failure). As an example, when administering an antibiotic to a client with diabetes, who has an infected toe, it may be difficult for the antibiotic to move through the blood vessels all the way to the cells of the toe that is infected.

Once the drug is in the bloodstream, a portion of it may exist as free drug, dissolved in plasma water. Some of the drug will be reversibly taken up by red cells, and some will be reversibly bound to plasma proteins. For many drugs, the bound forms can account for 95-98% of the total. This is important because it is the free drug that traverses cell membranes and produces the desired effect. It is also important because a protein-bound drug can act as a reservoir that releases the drug slowly and thus prolongs its action. With drug distribution, it is important to consider both the amount of free drug that is readily available to tissues, as well as the potential drug reserve that may be released over time.

Protein-Binding

A common factor impacting distribution of medication is plasma protein in the blood.  Albumin is one of the most important proteins in the blood.  Albumin levels can be decreased by several factors such as malnutrition and liver disease.  A certain percentage of almost every drug gets bound to plasma proteins when it initially enters the bloodstream and starts to circulate. The portion of the drug that gets “protein-bound” is inactive while it is bound, but the portion of the drug that escapes initial protein-binding becomes immediately “free” to bind to the target tissue and exert or block an action.

Clients taking several highly protein-bound medications often experience greater side effects.  Some drugs are able to competitively grab (or bind to) plasma proteins more easily than other drugs, thus taking up the available protein molecules first. This prevents secondary medications from binding strongly to protein and the intended target site. Instead, these medications float freely in the circulation without exerting action and increase the risk of side effects and toxicities.

Figure 1.4  Protein binding is like available seats on a bus 

Think of protein-binding like a bus stop (see Figure 1.4). Many passengers (or medication molecules) want to take a ride on the bus. Everyone is eager to get to their destination and interested in finding a seat.  Some passengers are stronger and will get in the seats first (like drug molecules with greater protein-binding ability bind to the protein).  Sometimes, there may not be enough seats on the bus, and some passengers are left at the bus stop. The passengers (medication molecules) who were left behind are “free” to move around and walk to their destination.  They may strike out on their own and get “snatched” (connected to a target receptor site) while on foot.  In a similar way, “free” drug particles that are not protein-bound are circulating in the bloodstream and connecting in a predictable fashion to receptor sites that have an affinity for that particular drug. These active drug molecules that did not bind to the protein (like those passengers that were unable to get a seat on the bus) will produce the first effect in the body. Over time, the medication molecules that are bound to the protein (like the passengers with seats on the bus) will get off the bus, start walking around, and get “snatched” to the receptor site that has affinity for them.

Blood-Brain Barrier

Medications destined for the central nervous system (the brain and spinal cord) face an even larger hurdle than protein-binding; they must also pass through a nearly impenetrable barricade called the blood-brain barrier. This blockade is built from a tightly woven mesh of capillaries that protect the brain from potentially dangerous substances, such as poisons or viruses.  Only certain medications that are made of lipids (fats) or have a “carrier” can get through the blood-brain barrier.

Research scientists have devised ways for certain medications to penetrate the blood-brain barrier. An example of this is the brand-named medication Sinemet®, which is a combination of two drugs: carbidopa and levadopa. Carbidopa is designed to carry the levadopa medication across the blood-brain barrier, where it enters the brain and is converted into dopamine to exert its effect on Parkinson’s disease symptoms.

Some medications inadvertently bypass the blood-brain barrier and impact an individual’s central nervous system function. For example, diphenhydramine (Benadryl®) is an antihistamine used to decrease allergy symptoms, however it can also cross the blood-brain barrier, depress the central nervous system, and cause the side effect of drowsiness. In the case of a person who has difficulty falling asleep, this drowsy side effect may be useful, but for another person it may be problematic, as they try to safely carry out daily activities.

Placental Barrier

It is always important to consider the effects of medication for clients who are pregnant or may become pregnant. The placenta is permeable to some medications, while others have not been specifically studied in pregnant clients. Some drugs can cause harm to the unborn fetus during any trimester. Therefore, it is imperative to always consult a healthcare provider regarding the safety of medications for use during pregnancy.  This imperative is assumed in the remaining chapters discussing medication classes, and nurses should always check the most recent, evidence-based drug references before administering medications during pregnancy.

Lifespan Considerations

Neonate & Pediatric: Fat content in young clients is decreased because of greater total body water. Additionally, for the growing pediatric client, the liver is still forming, protein-binding capacity is decreased, and the developing blood-brain barrier allows more drugs to enter the brain.

Older Adult: The aging adult client will experience a decrease in total body water and muscle mass. Body fat may increase and subsequently result in a longer duration of action for many medications. Serum albumin often also decreases, resulting in more active free drug within the body. This is one reason why many older adult clients require lower levels of medication.

Figure 1.5 Liver

Once a drug has been absorbed and distributed in the body, it will then be broken down by a process known as metabolism. The breakdown of a drug molecule usually involves two steps that take place primarily in the body’s chemical processing plant: the liver. See Figure 1.5 for an image of a human liver. Everything that enters the bloodstream—whether swallowed, injected, inhaled, absorbed through the skin, or produced by the body itself—is carried to this largest internal organ.

The biotransformations that take place in the liver are performed by the liver enzymes. Every one of your cells has a variety of enzymes, and each enzyme specializes in a particular job. Some enzymes break molecules apart, while others link small molecules into long chains. With drugs, the first step in metabolizing occurs through a process known as the first-pass effect, in which orally administered drugs are broken down in the liver and intestines.  This makes the substance easier to excrete in the urine. Medications made of protein that are swallowed or otherwise absorbed in the GI tract may quickly be deactivated by enzymes as they pass through the stomach and duodenum. If the drug enters the blood from the intestines, part of it will be broken down by liver enzymes, known as the first-pass effect, and some of it will escape to the general circulation to either be protein-bound (inactive) or stay free (and create an action at a receptor site). Thus, several doses of an oral medication may be needed to maintain enough active free drug in the circulation to exert the desired effect.

Many of the products of enzymatic breakdown, which are called metabolites, are less chemically active than the original molecule. For this reason, scientists refer to the liver as a “detoxifying” organ.   However, rather than being destroyed by liver enzymes, a few drugs are metabolized into an active form of an intended drug called a “prodrug.”  Prodrugs have chemical activities of their own—sometimes as powerful as those of the original drug. When prescribing certain drugs, healthcare providers must take into account these added effects. Once liver enzymes are finished working on a medicine, the now-inactive drug undergoes the final stage of its time in the body – excretion – as it exits via the urine or feces.

Lifespan Considerations

Neonate & Pediatric: The developing liver in infants and young children produces decreased levels of microsomal enzymes. This may result in a decreased ability of the young child or neonate to metabolize medications. In contrast, older children may experience increased metabolism and require higher doses of medications once the hepatic enzymes are fully produced.

Older Adult: Hepatic metabolism may experience a significant decline in the older adult. As a result, dosages should be adjusted according to the client’s liver function and anticipated metabolic rate. First-pass metabolism is also decreased with aging; therefore, older adults may have higher “free” circulating drug concentrations and be at higher risk for side effects and toxicities.

Attributions

• The first three paragraphs of the chapter and “Did you know the power of grapefruit juice?” were adapted from Medicines by Design by Allison Davis (US Department of Health and Human Services) and is in the public domain.

Excretion is the final stage of a medication interaction within the body. The body has absorbed, distributed, and metabolized the medication molecules – now what does it do with the leftovers? Remaining parent drugs and metabolites in the bloodstream are often filtered by the kidney, where a portion undergoes reabsorption back into the bloodstream, and the remainder is excreted in the urine. The liver also excretes byproducts and waste into the bile. Another potential route of excretion is the lungs. For example, drugs like alcohol and the anesthetic gases are often eliminated by the lungs.

Routes of Excretion

Now let’s further discuss the various routes of excretion from the body.

Kidney

The most common route of excretion is the kidney.  As the kidneys filter blood, the majority of drug byproducts and waste are excreted in the urine. The rate of excretion can be estimated by taking into consideration several factors:  age, weight, biological sex, and kidney function.  Kidney function is measured by lab values such as serum creatinine, glomerular filtration rate (GFR), and creatinine clearance.  If a client’s kidney function is decreased, then their ability to excrete medication is affected and drug dosages must be altered for safe administration.

Liver

As the liver filters blood, some drugs and their metabolites are actively transported by the hepatocytes (liver cells) to bile. Bile moves through the bile ducts to the gallbladder and then on to the small intestine. During this process, some drugs may be partially absorbed by the intestine back into the bloodstream.  Other drugs are biotransformed (metabolized) by intestinal bacteria and reabsorbed. Unabsorbed drugs and byproducts/metabolites are excreted via the feces. If a client is experiencing decreased liver function, their ability to excrete medication is affected and drug dosages must be decreased. Lab studies used to estimate liver function are called liver function tests and include measurement of the ALT and AST enzymes that the body releases in response to damage or disease.

Other Routes to Consider

Sweat, tears, reproductive fluids (such as seminal fluid), and breast milk can also contain drugs and byproducts/metabolites of drugs. This can pose a toxic threat, such as the exposure of an infant to breast milk containing drugs or byproducts of drugs ingested by their breastfeeding parent. Therefore, it is vital to check all medications with a healthcare provider before administering them to a parent who is breastfeeding.

Putting it all together…

Prescribing and administering medications in a safe manner to clients is challenging and requires a team effort by pharmacists, healthcare providers, and nurses.  In addition to the factors described in this chapter, there are many other considerations for safe medication administration that are further explained in the “Safety and Ethics” chapter.

Lifespan Considerations

Neonate & Pediatrics: Young clients have immature kidneys with decreased glomerular filtration, resorption, and tubular secretion. As a result, they do not clear medications as efficiently from the body.  Dosing for most medications used to treat infants and pediatric clients is commonly based on weight in kilograms, and a smaller dose is usually prescribed. In addition, pediatric clients may have higher levels of free circulating medication than anticipated and may become toxic quickly.  Therefore, frequent assessment of infants and children is vital for the early identification of drug toxicity.

Older Adult:  Kidney and liver function often decrease with age, which can lead to decreased excretion of medications. Subsequently, medication may have a prolonged half-life with a greater potential for toxicity due to elevated circulating drug levels.  Smaller doses of medications are often recommended for older clients due to these factors, which are commonly referred to as, “start low and go slow.”

Attributions

• The first paragraph and the paragraph under “Other Routes to Consider” were adapted from Principles of Pharmacology by Carl Rosow, David Standaert, & Gary Strichartz (republished by LibreTexts), which is licensed under CC BY-NC-SA 4.0 licence.

Complex Interactions

So far, we have learned the importance of pharmacokinetics in describing how the body absorbs, moves, processes, and eliminates a medication. Now let’s consider a drug’s impact on the body, a series of complex interactions known as pharmacodynamics.

When considering how the cells of the body respond to medications, it is important to remember that the majority of drugs bind to specific receptors on the surface or interior of cells. However, there are many other cellular components and non-specific sites that can serve as receptor sites where drugs can bind to create a response. For example, did you know that an osmotic laxative like magnesium citrate attracts and binds with water? This medication works to pull water content into the bowel and increases the likelihood of a bowel movement.

Other medications may inhibit specific enzyme binding sites in order to impact the functionality of a cell or tissue. For example, antimicrobial and antineoplastic drugs commonly work by inhibiting enzymes that are critical to the function of the cell. With blockage of the enzyme binding site, the cell microbe or neoplastic cell is no longer viable and cell death occurs.

Agonist and Antagonist Actions

Figure 1.7 Mechanism of Action

Understanding the mechanism of action, or how a medication functions within the body, is essential to understanding the processes medications go through to produce the desired effect (see Figure 1.7).  Drugs have agonistic or antagonistic effects.  A drug agonist binds tightly to a receptor to produce a desired effect.  A drug antagonist competes with other molecules and blocks a specific action or response at a receptor site. For example, the cardiac medication atenolol is a beta-1 receptor antagonist used to treat clients with hypertension or heart disease. Beta-1 receptor antagonist medications like atenolol produce several effects by blocking beta-1 receptors:  a negative inotropic effect occurs by weakening the contraction of the heart, thus causing less work of the heart muscle; a negative chronotropic effect occurs when the heart rate is decreased, and a negative dromotropic effect occurs when the conduction of the electrical charge in the heart is slowed.  Understanding the effects of a beta-1 antagonist medication allows the nurse to anticipate the expected actions of the medication and the client’s response.  Agonistic and antagonistic effects on receptors are further discussed in the “Autonomic Nervous System” chapter.

Attributions

• “Agonist and Antagonist Actions” was adapted from Principles of Pharmacology by Carl Rosow, David Standaert, & Gary Strichartz (republished by LibreTexts), which is licensed under CC BY-NC-SA 4.0 licence.

Prescription Medications, OTCs, Herbals, and Supplements

There is a variety of drug types and substances that clients may utilize for symptom management or to enhance wellness. Having an accurate record and knowledge of the different types of substances a client is taking is important to the client’s medical and nursing plan of care.  It is also important to note any substances that are prescribed, over-the-counter, or herbal that have been taken in the past month, as some medications have a long half-life and may still be in the body with the potential to interact with new medications.

A variety of substances available to the public include (but are not limited to) prescription medications (including brand name and generic drugs), over-the-counter medications, and herbals and supplements.

Prescription Medications

Drugs are prescribed by a licensed prescriber for a specific person’s use and regulated through the Health Products and Food Branch (HPFB) of Health Canada.  More information about HPFB approval of medications can be found on the Therapeutic Products Directorate page of the HPFB website.

Generic Medications

Generic medications can be safe and effective alternatives to their brand-name counterparts and often at a reduced cost.  By law, generic medications must have the same chemically active ingredient in the same dose (i.e., they must be “bio-equivalent”).  However, the excipients (the base substance that holds the active chemical ingredient into a pill form (such as talc) or the flavouring can be different. Some clients do not tolerate these differences in excipients very well.  When prescribing a medication, the provider must indicate that generic substitution is acceptable.  When studying medications in nursing school, it is important to know medications by their generic name, since the NCLEX exam does not currently include brand-name medications in their question format.  

Over-the-Counter Medications

Over-the-counter (OTC) medications do not require a prescription.  They can be bought at a store and may be used by multiple individuals.  OTC medications are also regulated through Health Canada. Some prescription medications are available for purchase as OTC in smaller doses.  For example, diphenhydramine (Benadryl) is commonly prescribed as 50 mg every 6 hours, and the prescription strength is 50 mg.  However, it can also be purchased OTC in 25 mg doses (or less for children.)

Herbals & Supplements

Herbs and supplements may include a wide variety of substances including vitamins, minerals, enzymes, and botanicals.  Supplements such as “protein powders” are marketed to build muscle mass and can contain a variety of substances that may not be appropriate for all individuals. Health Canada has a Natural and Non-prescription Health Products Directorate that is responsible for authorizing natural/non-prescription products for which safety, efficacy, and quality standards are in place . Some herbal and supplement substances are not regulated by Health Canada and most have not undergone rigorous scientific testing for safety for the public. While individuals may be tempted to try these herbals and supplements, there is no guarantee that they contain the ingredients listed on the label. It is also important to remember that there is a potential for adverse effects or even overdose if the herbal or supplement contains some of the same drug that was also prescribed to a client.

Onset, Peak, and Duration

Dosing considerations play an important role in understanding the effect that a medication may have on a client. During administration, the nurse must pay close attention to the desired effect and therapeutic response, as well as the safe dose range for any medication.  The nurse should have an understanding of medication efficacy in order to ensure its appropriateness.  If a nurse is provided different medication choices according to a provider’s written protocol, the nurse should select the option with the anticipated desired therapeutic response. Additionally, the nurse must be aware of the overall dose response based on the dosage selected.

Three additional principles related to the effect of a medication on a client are onset, peak, and duration.

Onset: the onset of medication refers to when the medication first begins to take effect

Peak : the peak of medication refers to the maximum concentration of medication in the body, and the point at which the client shows evidence of greatest therapeutic effect

Duration: the duration of medication refers to the length of time the medication produces its desired therapeutic effect

Consider this client care example and apply the principles of onset, peak, and duration: Gurmeet, a 67-year-old female client, who has just undergone hip replacement surgery earlier today, rings the call light to request medication for pain. She notes her pain is “excruciating, a definite 9 out of 10.” Her brow is furrowed, and she is grimacing in obvious discomfort. As the nurse providing care for Gurmeet, you examine her post-operative medication orders and consider the pain medication options available to you. In reviewing the various options, it is important to consider how quickly a medication will work (onset), when the medication will reach maximum effectiveness (peak), and how long the pain relief will last (duration). Understanding these principles is important in effectively relieving the client’s pain and constructing an overall plan of care.

Duration and Dosing

Now let’s consider the implication of duration and dosing. Remember the duration of medication is correlated with the elimination. If a medication has a short half-life (and thus is eliminated more quickly from the body), the therapeutic effect is shorter. These medications may require repeated dosing throughout the day in order to achieve steady blood levels of active free drug and a sustained therapeutic effect.  Other medications have a longer half-life (and thus a longer therapeutic duration) and are only given once or twice per day. For example, oxycodone immediate release is prescribed every 4 to 6 hours for the therapeutic effect of immediate relief of severe pain, whereas oxycodone ER (extended-release) is prescribed every 12 hours for the therapeutic effect of sustained relief of severe pain.

Monitoring Therapeutic Drug Levels

Now that the basic concepts of medication onset, peak, and duration have been discussed, it is important to understand the value of the therapeutic window and therapeutic index in medication administration.

Figure 1.9 Therapeutic Window

Therapeutic Window

For every drug, there exists a dose that is minimally effective (the Effective Concentration) and another dose that is toxic (the Toxic Concentration). Between these doses is the therapeutic window,  where the safest and most effective treatment will occur (see Figure 1.9).  Think of this area as the dosing “sweet spot.”

For example, warfarin (Coumadin) is a medication used to prevent blood clotting and is monitored using a blood test called INR. Too high a dose of warfarin would cause the INR to increase above the therapeutic window and put the client at risk of bleeding. Conversely, too low a dose of warfarin would cause the INR to be below the therapeutic window and put the client at risk of clotting.  It is vital that the nurse frequently monitor INR levels for a client receiving warfarin to ensure the dosage appropriately reaches the therapeutic window and does not place the client at risk for bleeding or clotting.

Peak and Trough Levels

Now let’s apply the idea of the therapeutic window to the administration of medications requiring the monitoring of peak and trough levels, which is required in the administration of some IV antibiotics. It is important for the dosage of these medications to be titrated to achieve a desired therapeutic effect for the client.  Titration is often accomplished by closely monitoring the blood levels of the medication. A drug is said to be within the “therapeutic window” when the serum blood levels of an active drug remain consistently above the level of effective concentration (so that the medication is achieving its desired therapeutic effect) and consistently below the toxic level (so that no toxic effects are occurring). A peak drug level is drawn at the time when the medication is being administered and is known to be at the highest level in the bloodstream.  A trough level is drawn when the drug is at its lowest in the bloodstream right before the next dose is given. Medications have a predicted reference range of normal values for peak and trough levels. These numbers assist the pharmacist and provider in gauging how the body is metabolizing, protein-binding, and excreting the drug, and assist in the adjustment of the prescribed drug doses to keep the medication within the therapeutic window.  When administering IV medications that require peak or trough levels, it is vital for the nurse to time the administration of  the medication according to the timing of these blood draws.

Therapeutic Index

Therapeutic Index is a quantitative measurement of the relative safety of a drug.  It is a comparison of the amount of drug that produces a therapeutic effect versus the amount of drug that produces a toxic effect.

• A large (or high) therapeutic index number means there is a large therapeutic window between the effective concentration and the toxic concentration of a medication, so the drug is relatively safe.
• A small (or low) therapeutic index number means there is a small therapeutic window between the effective concentration and the toxic concentration.   A drug with a narrow therapeutic range (i.e., having little difference between toxic and therapeutic doses) often has the dosage titrated according to measurements of the actual blood levels achieved in the person taking it.  For example, clients who start taking phenytoin to control seizures have the drug levels in their blood stream measured frequently.

Monitoring the Effects

As medications are administered, the nurse should perform careful client assessments, trend the assessment results, and monitor for side effects or toxic adverse effects. Drug dosages should be evaluated for potency in action. Potency refers to the amount of the drug required to produce the desired effect.  A drug that is highly potent may require only a minimal dose to produce a desired therapeutic effect, whereas a drug that has low potency may need to be given at much higher concentrations to produce the same effect.  Consider the example of opioid versus non-opioid medications for pain control.  Opioid medications often have a much higher potency in smaller doses to produce pain relief; therefore, the overall dose required to produce a therapeutic effect may be much less than for other analgesics.

The nurse preparing to administer medications must also be cognizant of drug selectivity and monitor for potential side effects and adverse effects.  The selectivity of a drug refers to how readily the drug targets specific cells to produce an intended therapeutic effect.  Drugs that are selective will search out target sites to create a drug action, whereas non-selective drugs may impact many different types of cells and tissues, thus potentially causing side effects.   A side effect occurs when the drug produces effects other than the intended effect.  A side effect, although often undesirable, is generally anticipated by the provider and is a known unintended consequence of the medication therapy.  Conversely, there are occasional occurrences of unanticipated effects that are dangerous to the client.  These dangerous occurrences are known as adverse effects.  Adverse effects are relatively unpredictable, severe, and are reason to discontinue the medication.

Attributions

• “Monitoring Therapeutic Drug Levels” and “Monitoring the Effects” was adapted from Principles of Pharmacology by Carl Rosow, David Standaert, & Gary Strichartz (republished by LibreTexts), which is licensed under CC BY-NC-SA 4.0 licence.

Within this unit, you have been introduced to many concepts related to pharmacokinetics and pharmacodynamics. These basic concepts are important to understand as we move our study into closer examination of various medication classes, principles of administration, and consideration of how medications can be safely incorporated into the client’s plan of care.

Medication administration is an essential task that nurses perform while providing client care. However, safe medication administration is more than just a nursing task; it is a process involving several members of the health care team, as well as legal, ethical, social, and cultural issues. The primary focus of effective medication administration by all health professionals is client safety. Although many measures have been put into place over the past few decades to promote improved client safety, medication errors and adverse effects continue to be a common event. The World Health Organization (WHO) estimates, “Unsafe medication practices and medication errors are a leading cause of injury and avoidable harm in health care systems across the world. Globally, the cost associated with medication errors has been estimated at $42 billion USD annually.” This chapter will examine the safety and ethical foundations of medication administration by nurses, as well as the practice standards and cultural and social issues that must be considered to ensure the safe and effective administration of medication.

CNA Code of Ethics for Nurses

The Canadian Nurses Association (CNA) is a professional organization that represents the national and global interests of Canadian nurses. They represent registered nurses, nurse practitioners, licensed and registered practical nurses, registered psychiatric nurses, and retired nurses across all 13 provinces and territories. The CNA developed the Code of Ethics for Registered Nurses as a guide for carrying out nursing responsibilities in a manner consistent with quality in nursing care and the ethical obligations of the profession.

CNA Registered Nurse Practice Framework

The CNA publishes The Framework for the Practice of Registered Nurses in Canada. This framework promotes a common understanding of RN practice among nurses, students and stakeholders (including other health professionals, employers, educators, policy-makers and the public). Given the large number of regulated and unregulated care providers in Canada, it is essential for policy-makers, decision-makers and employers to clearly understand RN competencies and contributions as well as to know when RN care is the most appropriate. Each province and territory also has a regional governing body for nurses. These regional bodies are responsible for further outlining the scope of practice, practice standards, and professional standards for their registrants. The regulatory body in British Columbia is the British Columbia College of Nurses and Midwives

The CNA defines nursing as “the application of professional nursing knowledge, skills, and judgment for the purpose of: (a) promoting, maintaining, and restoring health; (b) preventing illness, injury, or disability; (c) caring for persons who are sick, injured, disabled, or dying; (d) assisting in pre-natal care, childbirth, and postnatal care; (e) health teaching and health counselling; (f) coordinating health care; or (g) engaging in administration, teaching, or research. A registered nurse is an individual who is educationally prepared and licensed by a province or territory to practice as a registered nurse. 

CNA Entry-level Competencies

CNA entry-level competencies describe a competent level of behaviour in the professional role. ^{A total of 101 competencies are grouped thematically under nine roles. Integration of all nine roles enables the entry-level registered nurse to provide safe, competent, ethical, compassionate, and evidence-informed nursing care in any practice setting. Some concepts are relevant to multiple roles. The roles include:}

1. Clinician: provide safe, competent, ethical, compassionate, and evidence-informed care across the lifespan in response to client needs; integrate knowledge, skills, judgment and professional values from nursing and other diverse sources into their practice.
2. Professional: commit to the health and well-being of clients; uphold the profession’s practice standards and ethics and be accountable to the public and the profession; demonstrate accountability, accept responsibility, and seek assistance as necessary for decisions and actions within the legislated scope of practice.
3. Communicator: use a variety of strategies and relevant technologies to create and maintain professional relationships, share information, and foster therapeutic environments.
4. Collaborator: play an integral role in the health-care team partnership.
5. Coordinator: coordinate point-of-care health service delivery with clients, the health-care team, and other sectors to ensure continuous, safe care.
6. Leader: influence and inspire others to achieve optimal health outcomes for all.
7. Advocate: support clients to voice their needs to achieve optimal health outcomes and support clients who cannot advocate for themselves.
8. Educator: identify learning needs with clients and apply a broad range of educational strategies towards achieving optimal health outcomes.
9. Scholar: demonstrate a lifelong commitment to excellence in practice through critical inquiry, continuous learning, application of evidence to practice, and support of research activities.

CNA Practice Standards

Compared to the other designations of regulated nurses, the standards of practice for registered nurses vary across Canada with no national framework identified. The next section will focus on the professional and practice standards in British Columbia as set out by BCCNM.

BCCNM Professional Standards and Practice Standards

Professional Standards are “one set of standards under the umbrella of BCCNM Standards of Practice, are statements about levels of performance that nurses are required to achieve in their practice”.

• Standard 1: Professional Responsibility and Accountability
• Standard 2: Knowledge-Based Practice
• Standard 3: Client-Focused Provision of Service
• Standard 4: Ethical Practice

Nurses are guided by professional standards in all aspects of their roles, including medication administration.

Practice standards guide and direct nurses’ practice. ​They set out levels of performance that BCCNM nurse registrants are required to achieve in their practice. There is a specific practice standard related to medication administration for nurses.

BCCNM Practice Standard for Medication

In British Columbia, the BCCNM has developed a practice standard for medication administration for all nurses. This practice standard outlines nurses’ accountabilities for providing safe nursing care to clients when performing activities involving medication.

Controls on Practice

Controls on practice explains the bases for nurses’ scope of practice. There are four levels of controls on registered nurses’ practice. All these components are required to provide quality, safe client care that is evidence-based.

1. Nurses (Registered) and Nurse Practitioners Regulation, which sets out the scope of practice in fairly broad strokes.
2. BCCNM standards, limits and conditions, which complement and further define and limit the scope of practice set out in the Regulation.
3. Employer/organizational policies, which may restrict registered nurses’ practice in a particular agency or unit.
4. An individual registered nurse’s competence to carry out a particular activity.

Figure 2.2 BCCNM Controls on Nursing Practice. [Image Description]

Image Description

Figure 2.2: BCCNM Controls on Nursing Practice.

1. Regulation & Legislation: Health Professionals Act, Nurses (Registered) and Nurse Practitioners Regulation, Nurses (Licensed Practical) Regulation, Nurses (Registered Psychiatric) Regulation
2. BCCNM Standards, Limits & Conditions: Responsibility of BCCNM
3. Organizational Policies: Responsibility of organization
4. Individual Nurse Competence: Responsibility of the nurse [Return to Figure 2.2]

Media Attributions

• Figure 2.2: “Controls on Nursing Practice” is copyrighted by British Columbia College of Nurses and Midwives. All rights reserved. Reprinted with permission.

There are many federal and provincial laws, as well as national guidelines, that have been established to protect public health and safety. This section will explain how Health Canada and provincial/territorial nursing governing bodies protect the public from medication harm.

Health Canada Health Products and Food Branch

To protect the public, the Health Products and Food Branch (HPFB) of Health Canada is responsible for regulating, evaluating and monitoring the safety, efficacy, and quality of therapeutic and diagnostic products available to Canadians. These products include drugs, medical devices, disinfectants and sanitizers with disinfectant claims. Some of the ways that the HPFB protects the public health regarding medications include: enforcing an official drug approval process based on evidence-based research; issuing safety warnings for medications with serious adverse reactions; and regulating over-the-counter (OTC) medications. Each of these actions is further explained below.

Developing New Drugs

Canadian consumers benefit from having access to the safest and most advanced pharmaceutical system in the world. Drug companies conduct extensive research and work to develop and test a drug and follow the Development and Approval Process of Drugs by Health Canada.

Health Canada Approval: What it Means

Health Canada approval of a drug means that data on the drug’s effects have been reviewed by the HPFB, and the drug is determined to provide benefits that outweigh its known and potential risks for the intended population.

The HPFB reviews all new drug submissions and all the information about the drug captured during the development process (quality, preclinical and clinical) and evaluates the risks of the drug versus its benefits to the Canadian population. More specifically, HPFB reviews information regarding the drug’s manufacturing, packaging and labelling, as well as information about the drug’s therapeutic claims and side effects. What doctors and clients will be told about the drug will also be reviewed, through the drug’s monographs and information sheets. All drugs allowed to be sold in Canada are reviewed to ensure that they meet the requirements of the Food and Drugs Act and its Regulations. Once these requirements are met, the drug developer/sponsor receives a Notice of Compliance, confirming the dossier’s compliance with the Food and Drugs Act and its Regulations.

Safety Warnings

The HPFB posts a database of safety alerts, public health advisories, press releases and other notices related to therapeutic health products. This database includes recalls from Health Canada, the Canadian Food Inspection Agency, and Transport Canada. In the United States, if a safety problem surfaces, Black Box Warnings are issued by the FDA and appear on a prescription drug’s label. The purpose is to call attention to serious or life-threatening risks.

Clinical Reasoning and Decision-Making Activity 2.3a

Levofloxacin is an antibiotic that received FDA approval (the US equivalent of HFPB). However, after the drug was on the market, it was discovered that some clients who took levofloxacin developed serious, irreversible adverse effects such as tendon rupture. The FDA issued a Black Box Warning with recommendations to reserve levofloxacin for use in clients who have no alternative treatment options for certain indications: uncomplicated UTI, acute exacerbation of chronic bronchitis, and acute bacterial sinusitis.

A nurse is preparing to administer medications to a client and notices that levofloxacin has been prescribed for the indication of pneumonia. There is no other documentation in the provider’s notes related to the use of this medication.

What is the nurse’s best response?

Note: Answers to these activities can be found in the “Answer Key” sections at the end of the book.

Drug Schedules Regulation

Because controlled substances have a greater chance of being misused, there are additional laws and procedures that must be followed when working with these medications. The federal government administers some regulations regarding controlled substances. Most controlled substance regulations, however, come from the provincial governments through the provincial Drug Schedules Regulation under the Pharmacy Operations and Drug Scheduling Act (PODSA). Nurses also have the authority to administer, dispense, and compound certain medications under the Nurses (Licensed Practical) Regulation, the Nurses (Registered) and Nurse Practitioners Regulation, and the Nurses (Registered Psychiatric) Regulation. It is important that nurses are aware of their standards of practice and regulations related to their licensing and regulation.

Scheduled Medications

The Drug Schedules Regulation under the Pharmacy Operations and Drug Scheduling Act places all substances that are regulated under existing federal law into one of five schedules. Scheduled medications are based on a substance’s medical use, the potential for misuse, and safety or dependence liability.

Many problems associated with drug misuse are the result of legitimately made controlled substances being diverted from their lawful purpose into illicit drug traffic.

Drug Diversion

Drug diversion involves the transfer of any legally prescribed controlled substance from the individual for whom it was prescribed to another person for any illicit use. The most common drugs diverted from the health care facility setting are opioids. Tampering is the riskiest and most harmful type of diversion. 

In some cases, drug diversion can occur by health care providers. Substance misuse by nurses is often unidentified, unreported, and untreated; nurses may continue to practice where their impairment may endanger the lives of their clients. BCCNM has established a professional and ethical responsibility to report a colleague’s suspected drug use. For more information about drug diversion in nurses visit BCCNM Duty to report: Narcotic diversion and substance abuse impairing practice.

Prescription Monitoring Programs (PMP)

In addition to drug diversion programs, prescription monitoring programs (PMP) have been established in several provinces to address prescription drug misuse, addiction, and diversion. A PMP “collects information about prescription and dispensing of controlled substances for the purposes of monitoring, analysis and education. In Canada, it is the responsibility of the provincial institutions to organize, maintain and run such programs”. By providing valuable information about controlled substance prescriptions that are dispensed in the province, it aids healthcare professionals in their prescribing and dispensing decisions. The PMP also fosters the ability of pharmacies, healthcare professionals, law enforcement agencies, and public health officials to work together to reduce the misuse and diversion of prescribed controlled substance medications.

Proper Drug Disposal

Figure 2.3 Controlled Substances Collection Receptacle

Health Canada Guidelines allow users to dispose of controlled substances in a safe and effective manner. A Johns Hopkins study on sharing of medication found that 60% of people had leftover opioids they hung on to for future use; 20% shared their medications; 8% would likely share with a friend; 14% would likely share with a relative; and only 10% securely locked their medication. Health Canada also has a Take Back Program in all provinces and territories that allows anyone to return unused medication at any time (see figure 2.3). Additionally, needle disposal bins (yellow bins) are given through pharmacies for people on injectable medications.

Clinical Reasoning and Decision-Making Activity 2.3b

A nurse is providing discharge education to a client who recently had surgery and has been prescribed hydrocodone/acetaminophen tablets to take every four hours as needed at home. The nurse explains that when the post-op pain subsides and the medication is no longer needed, it should be dropped off at a local pharmacy for disposal in a collection receptacle. The client states, “I don’t like to throw anything away. I usually keep unused medication in case another family member needs it.”

1. What is the nurse’s best response?

A nurse begins a new job on a medical-surgical unit. One of the charge nurses on this unit is highly regarded by her colleagues and appears to provide excellent care to her clients. The new nurse cares for a client that the charge nurse cared for on the previous shift. The new nurse asks the client about the effectiveness of the pain medication documented as provided by the charge nurse during the previous shift. The client states, “I didn’t receive any pain medication during the last shift.” The nurse mentions this incident to a preceptor who states, “I have noticed the same types of incidents have occurred with previous clients but didn’t want to say anything.”

 

2. What is the new nurse’s best response?

Note: Answers to these activities can be found in the “Answer Key” sections at the end of the book.

Attributions

• “Clinical Reasoning and Decision-Making Activity 2.3a” was adapted from Daily Med by U.S. National Library of Medicine, which is the public domain.

Social Determinants of Health

The Canadian Public Health Association (CPHS), has a set of social and economic factors that impact our population’s health. There are fourteen determinants of health identified including;

• Income and Income Distribution
• Education
• Unemployment and Job Security
• Employment and Working Conditions
• Early Childhood Development
• Food Insecurity
• Housing
• Social Exclusion
• Social Safety Network
• Health Services
• Aboriginal Status
• Gender
• Race
• Disability

These are important considerations when caring for people.  For example, patients that are unemployed may struggle to afford medications from the pharmacy.  Understanding how these determinants of health can have an impact on their quality of life and their ability to access health care including medication, allows the nurse to provide adequate supports and resources to improve the person’s social determinants of health and ultimately their health and wellness overall. Along with determinants of health, Canadian nurses must also understand the implications of cultural influences in nursing care.

Canada has become increasingly diverse in the last century. According to Statistics Canada 2016, approximately 7,674,580 people in Canada fit into the visible minority population in Canada. Though health indicators such as life expectancy and infant mortality have improved for many, some minorities experience a disproportionate burden of preventable disease, death, and disability compared with non-minorities.

The British Columbia College of Nurses and Midwives (BCCNM) and the College of Physicians and Surgeons of BC (CPSBC) have been tirelessly working towards a practice standard on cultural safety and humility. BCCNM values cultural diversity and supports universal health care that transcends differences with respect to the culture, values and preferences of the individual, family, group, community, and population. Diversity characterizes today’s healthcare environment, and nursing is responsive to the changing needs of our society. To effectively promote meaningful client outcomes that maximize the quality of life across the lifespan, nurses must embrace diversity and engage in culturally safe practice.

When providing culturally safe care, nurses must recognize the critical component of cultural humility. Cultural humility is self-reflection of our own personal bias as well as recognition of other systematic biases. When we change our lens from one of using our nursing role as a power position, we need to consider fostering a relationship between ourselves and our clients that is built on trust and openness.

Medication Administration and Cultural Safety

When administering medication, nurses build trust with their clients. Nurses must follow their scope of practice for medications but also recognize that it is vital to have their clients become key drivers in their own care. To create this relationship, nurses must consider cultural barriers that could impact the full engagement of the client, including language barriers, previous negative experience with medical staff, and distrust of health care. Utilizing open communication through the skills of relational practice allows nurses to develop a partnership in decision-making. Listening to the needs of the client initiates an open discussion that improves health outcomes through medication adherence and an understanding of key factors.

Health Literacy and Medication Administration

Health literacy is “the ability to access, understand, evaluate, and communicate information as a way to promote, maintain, and improve health in a variety of settings across the life course” 60% of adults in Canada find it challenging to obtain, understand, and act on health information or services in Canada. 

When providing education around medications, nurses must ensure that the content is at an appropriate level for the client to understand the key concepts; it is also useful to appeal to multiple learning styles, such as writing it out, diagrams and other visuals, or recall. For more information about cultural safety, health literacy, and medication administration, you can review the following resources.

1. Health Literacy: You talk to your patients but do they understand? The importance of health literacy in your practice. The Centre for Literacy offers a Health Literacy e-module.
2. Cultural Safety: Multiple Webinars to choose from. These webinars are free and sponsored through the BC Association for child development and intervention.

When a nurse administers medication, the ultimate goal is to provide client safety and prevent harm from medications. However, medical errors and adverse effects of medication therapy continue to be a significant problem in Canada. This section will discuss initiatives established by the Institute of Medicine (IOM), the World Health Organization (WHO), the Institute for Safe Medication Practices (ISMP) Canada, and British Columbia Patient Safety and Quality Council (BCPSQC).

Safety Culture

According to the Institute of Medicine, “The biggest challenge to moving toward a safer health system is changing the culture from one of blaming individuals for errors to one in which errors are treated not as personal failures, but as opportunities to improve the system and prevent harm.”  The British Columbia Patient Safety and Quality Council (BCPSQC) develops effective solutions for health care’s most critical safety and quality problems with a goal to ultimately achieving zero harm to clients. The Center has also been instrumental in creating a focus on a “Safety Culture” in health care organizations. A safety culture empowers staff to speak up about risks to clients and to report errors and near misses, all of which drive improvement in client care and reduce the incidence of client harm.

In addition to the BCPSQC, some health authorities in Canada also use electronic databases to collect and use evidence to support and sustain protocols that help identify drug misuse and see gaps (for example, the BC Patient Safety Learning System).

As a result of the focus on creating a safety culture, whenever a medication error or a “near-miss” occurs nurses should submit a safety event report according to their institution’s guidelines. The incident report triggers a root cause analysis to help identify not only what and how an event occurred, but also why it happened. When investigators are able to determine why an event or failure occurred, they can create workable corrective measures that prevent future errors from occurring.

Based on results from incident report data, the Canadian Patient Safety Institute (CPSI), in partnership with the ISMP Canada, created a Medication Safety Action Plan to accelerate improvements in safe medication use in Canada.  The action plan covers five major themes:

1. Reporting, learning and sharing – focusing on reporting medication safety events, but also actively and mindfully sharing results with relevant parties.
2. Evidence-informed practices – focusing on developing and implementing evidence-informed guidelines for clinical practice to improve medication safety.
3. Partnering with patients – shifting the professional culture to encourage open sharing of information between providers and clients.
4. Education – ensuring clients have access to plain-language resources related to medication safety, and ensuring each member of the interdisciplinary team has a clear understanding of their roles with medication safety.
5. Technology – integration of health care system technologies, while addressing privacy concerns.

The plan outlines clear goals and actions that health authorities can take in order to mitigate medication errors.

Reducing Medication Errors

The national focus on reducing medical errors has been in place for almost two decades. In Canada, researchers estimate that there are 70,000 preventable adverse events annually in hospitalized clients, and preventable mortalities in the range of 9,000 to 24,000. In response to this data, health organizations have aimed to break the cycle of inaction regarding medical errors by advocating a comprehensive approach to improving client safety.

Despite the progress made in client safety over the last few years, medication errors remain extremely common, and the national health care system continues to implement initiatives to prevent errors. In 2015, ISMP Canada published a report titled Medication Error and Patient Safety: A Systems Approach, reporting that more than 7.5% (or 187,500) patients in Canadian hospitals were seriously harmed by their care. ISMP Canada emphasized systems-based actions that health care organizations, providers, and policy-makers/regulators could take to improve medication safety. These recommendations included actions such as automation or computerization of medication dispensing, standardization of order sets, electronic order sets, and improved policies/guidelines on medication administration.  IOM and ISMP Canada also emphasize actions that individual clients can take to prevent medication errors, such as maintaining active medication lists and bringing their medications to appointments for review.

On a global scale, multiple interventions to address the frequency and impact of medication errors have already been developed, yet their implementation has varied.  In 2019, the World Health Organization (WHO) identified “Medication Without Harm” as a theme for the Global Patient Safety Challenge with the goal of reducing severe, avoidable medication-related harm by 50% over the next five years.  As part of this challenge, WHO has prioritized three areas to protect clients from harm, while maximizing the benefit from medication:

1. Medication safety in high-risk situations
2. Medication safety in polypharmacy
3. Medication safety in transitions of care

A summary of these three areas and the strategies to reduce harm is provided below.

Medication Safety in High-Risk Situations

Medication safety in high-risk situations includes high-risk medications, provider-client relations, and systems factors.

High-risk (High-Alert) Medications

High-risk medications are drugs that bear a heightened risk of causing significant client harm when they are used in error. Although mistakes may or may not be more common with these medications, the consequences of an error are more devastating to clients. High-risk medication can be remembered using the mnemonic “A PINCH.” Figure 2.5 describes these medications included with the “A PINCH” mnemonic.

Note: Based on research, the Institute of Safe Medication Practices (ISMP) has expanded this list. The list can be viewed at: ISMP List of High-Alert Medications in Acute Care Settings

Strategies for safe administration of high-alert medication include:

• Standardizing the ordering, storage, preparation, and administration of these products
• Improving access to information about these drugs
• Employing clinical decision support and automated alerts
• Using redundancies such as automated or independent double checks when necessary

Provider-Client Relations

In addition to high-risk medications, the second component of medication safety in high-risk situations includes provider and client factors. This component relates to either the health care professional providing care or the client being treated. Even the most dedicated health care professional is fallible and can make errors. The act of prescribing, dispensing, and administering medicine is complex and involves several health care professionals.

Clients also can present risk factors. For example, it is well-known that adverse drug events occur most often at the extremes of life (in the very young and in older people). In the older population, frail clients are likely to be receiving several medications concurrently, which adds to the risk of adverse drug events. In addition, the harm of some of these medication combinations may sometimes be synergistic and greater than the sum of the risks of harm to the individual agents. In neonates (particularly premature neonates), elimination routes through the kidney or liver may not be fully developed. The very young and the very old are also less likely to tolerate adverse drug reactions, either because their homeostatic mechanisms are not yet fully developed or because they may have deteriorated. Medication errors in children, where doses may have to be calculated in relation to body weight or age, are also a source of major concern. Additionally, certain medical conditions predispose clients to an increased risk of adverse drug reactions, particularly renal or hepatic dysfunction and cardiac failure. Interprofessional strategies to address these potential harms are based on a systems approach with a “prescribing partnership” between the client, the prescriber, the pharmacist, and the nurse.

Some other provider-related errors include: misinterpreting an abbreviation, misidentifying drugs due to look-alike labels and packages, mis-programming a pump due to a pump design flaw, or simply making a mental slip when distracted. We expand on a few of these, below. Other errors stem from systems problems and practice issues that are somewhat unique to environments where the interdisciplinary team is caring together for clients. 

Error-Prone Abbreviations

Error-prone abbreviations are abbreviations, symbols, and dose designations that have been reported through the ISMP National Medication Errors Reporting Program as being frequently misinterpreted and involved in harmful medication errors. ISMP Canada’s Do Not Use Dangerous Abbreviations, Symbols, and Dose Designations should never be used when communicating medical information. Some examples of abbreviations that were commonly used that should now be avoided are qd, qod, qhs, BID, QID, D/C, subq, and APAP.

Strategies to avoid mistakes related to error-prone abbreviations include not using these abbreviations in medical documentation. Furthermore, if a nurse receives a prescription containing an error-prone abbreviation, it should be clarified with the provider and the order rewritten without the abbreviation.

Do Not Crush List

The IMSP also maintains a list of oral dosage medication that should not be crushed, commonly referred to as the do not crush list. These medications are typically extended-release formulations.

Strategies for preventing harm related to oral medication that should not be crushed include requesting an order for a liquid form or a different route if the client cannot safely swallow the pill form.

Look-Alike and Sound-Alike (LASA) Drugs

ISMP maintains a list of drug names containing look-alike and sound-alike name pairs such as captopril and carvedilol. These medications require special safeguards to reduce the risk of errors and minimize harm. For a full list of these medications, you can review the following resource ISMP Look Alike-Sound Alike List of Medications

Safeguards may include:

• Using both the brand and generic names on prescriptions and labels
• Including the purpose of the medication on prescriptions
• Changing the appearance of look-alike product names to draw attention to their dissimilarities
• Configuring computer selection screens to prevent look-alike names from appearing consecutively

Systems Factors

In addition to high-risk medications and provider-client relations, systems factors also contribute to medication safety in high-risk situations. Systems factors, also called the environment in hospitals, can contribute to error-provoking conditions for several reasons. The unit may be busy or understaffed, which can contribute to inadequate supervision or failure to remember to check important information. Interruptions during critical processes (e.g., administration of medicines) can also occur, which can have significant implications for client safety. Tiredness and the need to multitask when busy or flustered can also contribute to error, and can be compounded by poor electronic medical record design. Preparing and administering intravenous medications is also particularly error-prone. Strategies for reducing errors include checking at each step of the medication administration process; preventing interruptions; electronic provider order entry; and utilizing prescribing assessment tools.

Medication Safety in Polypharmacy

Polypharmacy is the concurrent use of multiple medications. Although there is no standard definition, polypharmacy is often defined as the routine use of five or more medications. This includes over-the-counter, prescription and/or traditional, and complementary medicines used by a client. As the population ages, more people are likely to suffer from multiple long-term illnesses and take multiple medications. It is therefore essential to take a person-centered approach to ensure that medications are appropriate for the individual, to gain the most benefits without harm, and to ensure that clients are integral to the decision-making process.

Appropriate polypharmacy is present when:

• all medicines are prescribed for the purpose of achieving specific therapeutic objectives with which the client has agreed;
• therapeutic objectives are actually being achieved or there is a reasonable chance they will be achieved in the future; or
• medication therapy has been optimized to minimize the risk of adverse drug reactions, and the client is motivated and able to take all medicines as intended.

Inappropriate polypharmacy is present when:

• one or more medicines are prescribed that are not or no longer needed, either because there is no evidence-based indication, the indication has expired or the dose is unnecessarily high;
• one or more medicines fail to achieve the therapeutic objectives they are intended to achieve;
• a medicine or the combination of several medicines put the client at a high risk of adverse drug reactions; or
• the client is not willing or able to take one or more medicines as intended.

When clients move across care settings, medication review is important to prevent harm caused by inappropriate polypharmacy. The WHO’s report, titled Medication Safety in Polypharmacy, includes the questions that should be addressed during a medication review with a multidisciplinary approach that includes the nurse.

Medication Safety in Transitions of Care

A third area of the WHOMedications Without Harm initiative relates to medication safety during transitions of care.  View the interactive activity below to see how medications are reconciled during transitions of care from admission to discharge in a hospital setting.

Medication errors can occur during these changes in settings. Figure 2.6 is an image from the WHO showing ranges of the percentage of errors that occur during common transitions of care.

Fig 2.6 Medication discrepancies at various transitions of care [Image Description]

Some suggested strategies for improving medication safety include:

• Implement formal structured processes for medication reconciliation at all transition points of care. Steps of effective medication reconciliation include: building the best possible medication history by interviewing the client and verifying with at least one reliable information source; reconciling and updating the medication list; and communicating with the client and future health care providers about changes in their medications.
• Partner with clients, families, caregivers, and health care professionals to agree on treatment plans, ensuring clients are equipped to manage their medications safely and clients have an up-to-date medication list.
• Where necessary, prioritize clients at high risk of medication-related harm for enhanced support, such as post-discharge contact by a nurse.

Supplementary Resources

Below are supplementary learning resources related to client safety and error prevention during medication administration.

Client example of medical errors.

Watch the Josie King Story about medical errors to gain perspective from a client who has experienced a medical error.

Questions a nursing student may be asked about medications

As a student, when you prepare to administer medications to your clients during clinical care, your instructor will ask you questions to ensure safe medication administration.

See an example of the typical questions that a clinical instructor might ask. Enhancing Medication Safety in Clinical: A Video for Students and Nursing Faculty

BC Patient Safety and Quality Council

The BSPSQC was the basis for many references for this chapter; it also has several other resources that may be beneficial to your learning about client safety related to medication administration.

The Council provides system-wide leadership to efforts designed to improve the quality of health care in British Columbia. Through collaborative partnerships with health authorities, clients, and those working within the health care system, BCPSQC promotes and informs a provincially coordinated, client-centered approach to client safety and quality. The Council also provides numerous resources for health care professionals to help build competence in safety and quality. To view and register for upcoming learning programs related to client safety and quality, visit the BCPSQC website.

Image Description

Fig 2.6 description: This is is a circle divided into 4 quadrants to depict 4 areas where medication discrepancy can occur: 

1. Community: 14-98% of community-dwelling older person and 27-57% of those in residential aged care facilities had medication discrepancies. 
2. Hospital admission: 3-97% of adult patients and 22-72% of paediatric patients had at least one medication discrepancy at admission. 
3. Discharge: 25-80% of patients had at least one medication discrepancy at discharge. 
4. Transfer within hospital: 62% of patients had at least one unintentional medication discrepancy at transfer between units in hospital. [Return to Fig 2.6]

Attributions

• “Systems Factors” was adapted from Medication Safety in High Risk Situations by World Health Organization, which is licensed under a CC BY-NC-SA 3.0 licence.
• “Medication Safety in Polypharmacy” was adapted from Medication Safety in Polypharmacy by World Health Organization, which is licensed under a CC BY-NC-SA 3.0 licence.

Have you ever been prescribed an antibiotic for an infection and asked, “Why do I have to finish taking all these pills when I already feel better”? Or, perhaps you wondered why the healthcare provider chose a certain medication over another or why the pharmacist told you to avoid certain foods when taking a certain antibiotic.

You may have had these questions in your own healthcare experiences. It is important to remember that if you have these questions, many of your patients will as well. Learning about the various types of antimicrobials and how they work will help you provide better health education to your patients.

Attributions

• The section on the ancient use of antimicrobial agents was adapted from “History of Chemotherapy and Antimicrobial Discovery” in Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (© 2022 OpenStax), which is licened under a CC BY 4.0 licence.

Concepts Related to Infection

For the purposes of this concept discussion, the Concept of Infection is defined as “the invasion and multiplication of microorganisms in body tissues, which may be clinically unapparent or result in local cellular injury”. This resource provides a basic introduction to the concept of infection as it relates to pharmacology. The example concept map below provides a summary of the key information necessary to understand infection. You can revisit this map after you have completed the chapter. The information for the map was informed by several resources.

Fig 3.2a: Concept Map for Infection [Image Description]

Before learning about medications that are used to treat infections in our clients, it is important for nurses to first understand the basics of microbiology.  Bacteria are found in nearly every habitat on earth, including within and on humans. Most bacteria are harmless or considered helpful, but some are pathogens.  A pathogen is defined as an organism causing disease to its host. Pathogens, when overgrown, can cause significant health problems or even death for your clients.

Bacteria may be identified when a client has an infection by using a culture and sensitivity test or a gram stain test. Antimicrobials may be classified as broad-spectrum or narrow-spectrum, based on the variety of bacteria they effectively treat.  Additionally, antibiotics may be bacteriostatic or bactericidal in terms of how they target the bacteria. Finally, the mechanism of action is also considered in the selection of an antibiotic.

In addition to antibiotics, antimicrobials also include medications used to treat viruses and fungi.  Each of these topics will be discussed in more detail below, along with the issue of drug resistance.

Concepts Related to Bacterial Infections

Culture and Sensitivity

When a client presents signs or symptoms of an infection, healthcare providers will begin the detective work needed to identify the source of the infection.  A culture is a test performed to examine different body substances for the presence of bacteria or fungus. These culture samples are commonly collected from a client’s blood, urine, sputum, wound bed, etc.  Nurses are commonly responsible for the collection of culture samples and must be conscientious to collect the sample prior to the administration of antibiotics.  Antibiotic administration prior to a culture can result in a delayed identification of the organism and complicate the client’s recovery. Once culture samples are collected, they are then incubated in a solution that promotes bacterial or fungal growth and spread onto a special culture plate.  Clinical microbiologists subsequently monitor the culture for signs of organism growth to aid in the diagnosis of the infectious pathogen.  A sensitivity analysis is often performed to select an effective antibiotic to treat the microorganism.  If the organism shows resistance to the antibiotics used in the test, those antibiotics will not provide effective treatment for the client’s infection.  Sometimes a client may begin antibiotic treatment for an infection, but will be switched to a different, more effective antibiotic, based on the culture and sensitivity results.

Gram-Positive vs. Gram-Negative

A gram stain is another type of test that is used to assist in classification of pathogens.  Gram stains are useful for quickly identifying if bacteria are “gram-positive” or “gram-negative,” based on the staining patterns of their cellular walls. Utilizing gram stain allows microbiologists to look for characteristic violet (Gram +) or red/pink (Gram -) staining patterns when they examine the organisms under a microscope. Identification of bacteria as gram-positive or gram-negative assists the healthcare provider in quickly selecting an appropriate antibiotic to treat the infection.

Sample Gram-Positive Infections

Figure 3.2b Gram Stain Specimen Streptococcus

Streptococcus, the name of which comes from the Greek word for twisted chain, is responsible for many types of infectious diseases in humans. Streptococcus is an example of a Gram + infection and is identified by its ability to lyse, or breakdown, red blood cells when grown on blood agar.

S. pyogenes is a type of  β-hemolytic Streptococcus. This species is considered a pyogenic pathogen because of the associated pus production observed with infections it causes (see Figure 3.2b for an image of Streptococcus undergoing gram staining). S. pyogenes is the most common cause of bacterial pharyngitis (strep throat); it is also a common cause of various skin infections that can be relatively mild (e.g., impetigo) or life-threatening (e.g., necrotizing fasciitis, also known as flesh-eating disease).

Figure 3.2c Staphylococcus aureus illustrates the typical “grape-like” clustering of cells

Staphylococcus is a second example of a Gram + bacteria. The name “Staphylococcus” comes from a Greek word for bunches of grapes, which describes their microscopic appearance in culture. Strains of S. aureus cause a wide variety of infections in humans, including skin infections that produce boils, carbuncles, cellulitis, or impetigo.  Many strains of S. aureus have developed resistance to antibiotics. Some antibiotic-resistant strains are designated as methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) . These strains are some of the most difficult to treat because they exhibit resistance to nearly all available antibiotics, not just methicillin and vancomycin. Because they are difficult to treat with antibiotics, infections can be lethal. MRSA and VRSA are also contagious, posing a serious threat in hospitals, nursing homes, dialysis facilities, and other places where there are large populations of elderly, bedridden, and/or immunocompromised individuals. See Figure 3.2c for an image of Staphylococcus bacteria microscopically.

Sample Gram-Negative Infections

Figure 3.2d Neisseria meningitidis growing in colonies on a chocolate agar plate

Gram negative bacteria often grow between aerobic and anaerobic areas (such as in the intestines). Some gram-negative bacteria cause severe, sometimes life-threatening disease. The genus Neisseria, for example, includes the bacteria N. gonorrhoeae, the causative agent of the sexually transmitted infection gonorrhea, and N. meningitides, the causative agent of bacterial meningitis. See Figure 3.2d for an image of Neisseria meningitides. Another common gram-negative infection that is seen in hospitalized clients is Escherichia coli  (E. Coli).  This is a frequent culprit for urinary tract infections due to its presence in the GI tract.

Broad-Spectrum vs. Narrow-Spectrum Antimicrobials

Spectrum of activity is one of the factors that is useful when selecting antibiotics to treat a client’s infection. A narrow-spectrum antimicrobial targets only specific subsets of bacterial pathogens. For example, some narrow-spectrum drugs target only gram-positive bacteria, but others target only gram-negative bacteria. If the pathogen causing infection has been identified in a culture and sensitivity test, it is best to use a narrow-spectrum antimicrobial and minimize collateral damage to the normal microbacteria.

A broad-spectrum antimicrobial targets a wide variety of bacterial pathogens, including both gram-positive and gram-negative species, and is frequently used to cover a wide range of potential pathogens while waiting for the laboratory identification of the infecting pathogen. Broad-spectrum antimicrobials are also used for polymicrobial infections (a mixed infection with multiple bacterial species) or as prophylactic prevention of infections with surgery/invasive procedures. Finally, broad-spectrum antimicrobials may be selected to treat an infection when a narrow-spectrum drug fails because of development of drug resistance by the target pathogen.

Figure 3.2e Clostridium difficile, a gram-positive, rod-shaped bacterium, causes severe colitis and diarrhea, often after the normal gut microbiota is eradicated by antibiotics

One risk associated with using broad-spectrum antimicrobials is that they will also target a broad spectrum of the normal microbacteria, potentially causing diarrhea.  They also increase the risk of a superinfection , a secondary infection in a client having a preexisting infection. A superinfection develops when the antibacterial intended for the preexisting infection kills the protective microbiota, allowing another pathogen resistant to the antibacterial to proliferate and cause a secondary infection. Common examples of superinfections that develop as a result of antimicrobial use include yeast infections (candidiasis) and pseudomembranous colitis caused by Clostridium difficile (C-diff), which can be fatal. Probiotics, such as lactobacillus, are commonly used for individuals with C-diff to introduce normal bacteria into the gastrointestinal system and improve bowel function. See Figure 3.2e for an image of C-diff microscopically.

Antibacterials’ Actions – Bacteriostatic vs. Bactericidal

When a provider selects an antibacterial drug, it is important to consider how and where the drug will ultimately target the bacteria.  Antibacterial drugs can be either bacteriostatic or bactericidal in their interactions with the offending bacteria. Bacteriostatic drugs cause bacteria to stop reproducing; however, they may not ultimately kill the bacteria.  In contrast, bactericidal  drugs kill their target bacteria.

The decision about whether to use a bacteriostatic or bactericidal drug often depends on the type of infection and the overall immune status of the client. In a healthy client with strong immune defences, both bacteriostatic and bactericidal drugs can be effective in achieving clinical cure. However, when a client is immunocompromised, a bactericidal drug is essential for the successful treatment of infections. Regardless of the immune status of the client, life-threatening infections such as acute endocarditis require the use of a bactericidal drug to eliminate all offending bacteria.

Mechanism of Action

Another consideration in the selection of an antibacterial drug is the drug’s mechanism of action.  Each class of antibacterial drugs has a unique mechanism of action, the way in which a drug affects microbes at the cellular level. For example, cephalosporins act on the integrity of the cell wall.  In contrast, aminoglycosides impact ribosome function and inhibit protein synthesis, which stops the proliferation of cells. See Figure 3.2f for a summary of how various antibiotics affect the cell wall, the plasma membrane, the ribosomes, the metabolic pathways, or DNA synthesis of bacteria.

Figure 3.2f Various mechanisms of actions of antimicrobial medication. [Image Description]

Viral Infections

Antiviral

Similar to antibacterial medications, antiviral drugs directly impact the interaction and reproduction of the offending microorganism.  Antibacterial medications are required for treating bacterial infections; antivirals treat specific viral infections.  For example, oseltamivir (Tamiflu) is commonly prescribed to treat influenza.  Unlike antimicrobials, antiviral medications do not kill the offending virus, but they work to reduce replication and development of the virus.

Review this quick video on how antiviral medications work:

Fungal Infections

Antifungal

Antifungal, or antimycotic agents, are medications that are used to treat fungal infections.  These medications work by killing the cells of the fungus or inhibiting the reproduction of the cells.  Unlike antibacterial and antiviral medications, many antifungals are applied topically to the affected area.  Fungal infections commonly affect surface areas of the body, including the toes, nails, mouth, groin, etc. For example, Candida albicans is a type of fungi that when overgrown in the mouth produces oral thrush.  Clients experiencing thrush may be prescribed oral antifungal swish and spit medication such as nystatin.

Drug Resistance

Although there is a wide availability of medications that are useful for treating infection, greater limitations in effectiveness are being seen.  It is estimated that 1 in 16 Canadians admitted to hospital will develop an infection from a resistant superbug.

Prevention Strategies

In Canada and many other countries, most antimicrobial drugs are self-administered by clients at home. Unfortunately, many clients stop taking antimicrobials once their symptoms dissipate and they feel better. If a 10-day course of treatment is prescribed, many clients only take the drug for 5 or 6 days, unaware of the negative consequences of not completing the full course of treatment.

The Problem: A shorter course of treatment not only fails to kill the target organisms to the expected levels but also assists in creating drug-resistant variants within the body.  A client’s nonadherence amplifies drug resistance when the recommended course of treatment is long.

The overprescription of antimicrobials also contributes to antibiotic resistance. Clients often demand antibiotics for diseases that do not require them, like viral colds and ear infections. Pharmaceutical companies aggressively market drugs to physicians and clinics, making it easy for them to give free samples to clients, and some pharmacies even offer certain antibiotics free to low-income clients with a prescription.

In recent years, various initiatives have aimed to educate parents and clinicians about the judicious use of antibiotics. However, previous studies have shown the parental expectations for antimicrobial prescriptions for children actually increased.

One possible solution that is being explored is a regimen called directly observed therapy (DOT), which involves the supervised administration of medications to clients. Clients are either required to visit a health-care facility to receive their medications, or health-care professionals must administer medication in clients’ homes or another designated location. DOT has been implemented in many cases for the treatment of TB and has been shown to be effective; indeed, DOT is an integral part of WHO’s global strategy for eradicating TB.  If interested, more information about DOT programs in Canada for TB therapy is available through the Public Health Agency of Canada.

But is this a practical strategy for all antibiotics? Would clients taking penicillin, for example, be more or less likely to adhere to the full course of treatment if they had to travel to a health-care facility to receive each dose? Who would pay for the increased cost associated with DOT? When it comes to overprescription, should providers or drug companies be policed when it comes to overprescribing antibiotics to enforce best practices? What group should assume this responsibility, and what penalties would be effective in discouraging overprescription?

This is a complex issue with no clear, easy solution.  However, what is clear is that all clients need extensive education regarding the judicious and complete use of medications to increase adherence and decrease the opportunity for antimicrobial resistance.

Clinical Reasoning and Decision-Making Activity 3.2a

Reflecting on current healthcare challenges regarding the ongoing emergence of antimicrobial-resistant organisms, what actions could you take within your nursing practice to help prevent drug resistance?

Note: Answers to the activities can be found in the “Answer Key” sections at the end of the book.

Image Description

Figure 3.2a – Concept Map for Infection: This flowchart describes the Concept of Infection.  In the centre of the chart, Infection is defined.

The definition of the Concept of Infection is: the invasion and multiplication of microorganisms in body tissues, which may be clinically unapparent or result in local cellular injury

Next, there are 4 arrows pointing from the definition to the Scope of Infection.  The scope is divided into 4 categories: Bacterial, Viral, Fungal and Parasitic.

Next, one arrow points from the definition to the Variation of Infection.  Types of infection can vary by severity, location, host response to treatment, and potential for debilitating consequences.

Next, the Physiological Process of Infection is outlined.  The steps included in the process are: 1) Pathogen invades body; 2) Immune responses initiated to minimize tissue and organ damage; 3) vasodilation, increased vascular permeability, WBC recruitment, phagocytosis, cytokine release.

From the Physiological Process, an arrow points down towards Assessment for Infection.  Here, a summary of site-specific and general signs and symptoms is listed, as well as laboratory studies used to confirm presence of infection. The symptom listed are: redness, heat, swelling, pain, exudate, cough, fever, fatigue.  The laboratory studies listed are:  C+S, CBC (↑ WBC count), radiographic studies, ↑ CRP, ESR, Serological tests for virus or ab’s)

Finally, an arrow connects Assessment to Management of Infection. The treatment/management depends on the cause and symptoms.  For Bacterial infection – treat with antibiotics, for Viral infection – treat with antivirals, for Fungal infection – treat with antifungals, for Parasitic infection – treat with antiprotazoals. [Return to Figure 3.2a]

Figure 3.2f Various mechanisms of actions of antimicrobial medication: A pill representing antimicrobial medication is sliced open to reveal what looks like the parts of a cell. The image provides examples of different antimicrobial medications that affect these parts of the cell. Parts and processes of the cell affected by antimicrobial medication include:

• The cell wall, which is impacted by:
  • β-lactams, such as penicillins, cephalosporins, monobactams, carbapenems;
  • Glycopeptides, such as vancomycin;
  • Bacitracin.
• The plasma membrane, which is impacted by:
  • Polymyxins, such as polymyxin B, colistin;
  • Lipopeptides, such as daptomycin.
• Ribosomes, including:
  • 30S subunit, which is affected by aminoglycosides, tetracyclines;
  • 50S subunit, which is affected by macrolides, lincosamides, chloramphenicol, oxazolidinones.
• Metabolic pathways, including:
  • Folic acid synthesis, which is affected by sulfonamides, sulfones, trimethoprim;
  • Mycolic acid synthesis, which is affected by izoniazid.
• DNA synthesis, which is impacted by:
  • Fluoroquinolones, such as ciprofloxacin, levofloxacin, moxifloxacin.
• RNA synthesis, which is impacted by:
  • Rifamycins, including rifampin.

[Return to Figure 3.2f]

Attributions

• This chapter was adapted from Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (© 2022 OpenStax), which is licened under a CC BY 4.0 licence.

Now that we have reviewed antimicrobial basics, we will take a closer look at specific antimicrobial classes and administration considerations, therapeutic effects, adverse effects, and specific teaching needed for each class of antimicrobials. But before we do that, let’s reexamine the importance of the nursing process in guiding the nurse who administers antimicrobial medications.  The nursing process consists of assessment, diagnosis, outcome identification, planning, implementation of interventions, and evaluation. Because diagnosis, outcome identification, and planning are specifically tailored to the individual client, we will broadly discuss considerations related to assessment, implementation of interventions, and evaluation when administering antimicrobials.

Assessment

Although there are numerous details to consider when administering medications, it is always important to first think more broadly about what you are giving and why.  As a nurse who is administering an antimicrobial, you must remember some important broad considerations.

First, let’s think of the WHY? Recognizing cues…

Antimicrobials are given to prevent or treat infection. If a client is prescribed an antimicrobial, an important piece of the nursing assessment is to recognize and analyze cues.  The nurse should look for signs and symptoms of infection, and always know WHY the client is receiving an antimicrobial to effectively evaluate whether the client is improving or deteriorating. Remember, the nurse must assess how this medication is working, and having pre-administration assessment information is an important part of this process.

In order to define a baseline, typical data that a nurse collects at the start of a shift include:

• temperature
• heart rate
• blood pressure
• respiratory rate, and
• white blood cell count.

Focused assessments are then made based on the type of infection. For example, if it is a wound infection, the wound should be assessed for redness, inflammation, drainage type and amount, and pain. If it is a respiratory infection, the nurse should assess the client’s lung sounds, and type/consistency of respiratory expectorate. If a client has a urinary tract infection (UTI), the urine and symptoms related to a UTI (pain with urination, cloudy urine, foul-smelling urine) should be assessed.

The following image summarizes some common signs and symptoms of infection (by system) that a nurse needs to monitor for.

Figure 3.4 Summary of common signs and symptoms of infection. [Image Description]

Additionally, whenever a client has an infection, it is important to continually monitor for the development of sepsis, a life-threatening condition caused by severe infection.  As you recall from the previous chapter, early signs of sepsis include new-onset confusion, elevated heart rate, decreased blood pressure, increased respiratory rate, and elevated fever.

Additional baseline information to collect prior to the administration of any new medication order includes a client history, current medication use, including herbals or other supplements, and history of allergy or previous adverse response. Many clients with an allergy to one type of antimicrobial agent may experience cross-reactivity to other classes. This information should be appropriately communicated to the prescribing provider prior to the administration of any antimicrobial medication.

When a nurse has completed a thorough assessment, they are able to prioritize their concerns/hypotheses before implementing further intervention.

Interventions

With administration of the antimicrobial medication, it is important for the nurse to anticipate any additional interventions associated with the medications. For example, antimicrobials often cause gastrointestinal upset (GI) such as nausea, diarrhea, etc.  The nurse may need to refine their assessments and interventions, accordingly. The client should be educated about these potential side effects, and proper interventions should be taken to minimize these occurrences. For example, the nurse may instruct the client to take certain antimicrobials with food to diminish the chance of GI upset, whereas other medications should be taken on an empty stomach for optimal absorption.

Hypersensitivity/allergic reactions are always a potential adverse reaction, especially when administering the first dose of a new antibiotic, and the nurse should monitor closely for these symptoms and respond appropriately by immediately notifying the prescriber.  Hypersensitivity reactions are immune responses that are exaggerated or inappropriate to an antigen and can range from itching to anaphylaxis.  Anaphylaxis is a medical emergency that can cause life-threatening respiratory failure.  Early signs of anaphylaxis include, but are not limited to, hives and itching, the feeling of a swollen tongue or throat, shortness of breath, dizziness, and low blood pressure.

Evaluation

Finally, it is important to always evaluate the client’s response to a medication. With antimicrobial medications, the nurse should assess for the absence of or decreasing signs of infection, indicating the client is improving. It is important to document these findings to reflect the client’s trended response.

Additionally, it is also important for the nurse to promptly identify and communicate signs of worsening infection to the provider. For example, increasing white blood cell count, temperature, heart rate, and respiratory rate may indicate that the client’s body is experiencing a life-threatening response to the infection. These signs of worsening clinical assessment require prompt intervention to prevent further clinical deterioration. Additionally, clients receiving antibiotics should be closely monitored for developing a complication called “C. diff,” resulting in frequent, foul-smelling stools. C. diff stands for Clostridioides difficile, which is a spore-forming, gram-positive bacterium that colonizes the human intestinal tract after the normal gut flora has been disrupted (frequently in association with antibiotic therapy). C. diff is one of the most common health care-associated infections and a significant cause of morbidity and mortality, especially among older adult hospitalized clients. Management of C-diff requires the implementation of modified contact precautions, including the use of soap and water, not hand sanitizer (as this does not kill the spores), as well as antibiotic therapy.

Image Description

Figure 3.4 Summary of common signs and symptoms of infection: A diagram showing a cartoon version of a human body. This diagram gives an internal view of the body, including organs, veins and arteries, and bones. Indicating various points on the body, this diagram lists common signs and symptoms of infection based on where in the body they can originate. These include:

• Respiratory (lungs): crackles, tachypnea, decreasing oxygen saturation, atelectasis.
• Gastrointestinal (digestive system): diarrhea, N/V (nausea and vomiting), stool sample positive.
• Incision/wound: purulent drainage, erythema, swollen, painful, warm.
• Central nervous system (brain): confusion, fever.
• Cardiac (heart): tachycardia, hypotension.
• Skin: red, swollen, painful, purulent, warm; phlebitis.
• Genitourinary (bladder): cloudy urine, dysuria, frequency, urgency, pelvic pain, urinalysis positive.
• Systemic: fever, hypotension, fatigue.

[Return to Figure 3.4]

The administration of antimicrobial drug therapy involves special considerations to ensure that the therapeutic drug effect is achieved while maintaining client safety and minimizing complications.

Let’s consider some of the variables that may impact antimicrobial administration:

Figure 3.5a Medication concentration over time demonstrates half-life

Half-Life

Many antimicrobial medications are administered to ensure that a certain therapeutic level of medication remains in the bloodstream, and may require interval or repeated dosing throughout the day. For example, the half-life, or rate at which 50% of a drug is eliminated from the plasma, can vary significantly between drugs. Some drugs have a short half-life of only 1 hour and must be given multiple times a day, but other drugs have half-lives exceeding 12 hours and can be given as a single dose every 24 hours. Although a longer half-life can be considered an advantage for an antibacterial when it comes to convenient dosing intervals, the longer half-life can also be a concern for a drug with serious side effects. Medications that have longer half-life and more concerning side effects will exert these side effects over a longer period of time.

See Figure 3.5a for an illustration of half-lives and the time it takes for a medication to be eliminated from the bloodstream.

Lifespan Considerations

A majority of medications are calculated specifically based on the client’s size, weight, and renal function. Client age and size are especially vital in pediatric clients. A child’s stage of development and the size of their internal organs will greatly impact how the body absorbs, digests, metabolizes, and eliminates medications.

Liver & Renal Function

Additionally, there are many antimicrobial medications that will require tailored dosing based on individual client response and the potential impact of the medication on the client’s liver and renal function. For more information about the effects of liver and renal function on medications, refer to Chapter 1 regarding metabolism and excretion.  Oftentimes, pharmacists and providers will collect peak and trough drug blood levels to determine how an individual client’s body is responding to an antimicrobial. Follow-up interval dosing is then prescribed based on these blood levels. This is especially important for older adults or those with known liver/renal impairment. Individuals with diminished liver and renal function are more prone to drug toxicity because of the reduced ability of the body to metabolize or clear medications from the body. For more information about peak and trough levels, refer to Chapter 1 regarding medication safety.

Dose Dependency/Time Dependency

The goal of antimicrobial therapy is to select an optimal dosage that will result in clinical cure, while reducing complications or significant side effects. Many medications may be dose-dependent. This means that there is a more significant killing of the bacterial with increasing levels of the antibiotic.  For example, fluroquinolones are dose-dependent medications with the treatment goal to optimize the amount of the drug. Other medications are time-dependent. Time-dependent medications have optimal bacterial killing effect at lower doses over a longer period of time. Time-dependent antimicrobials exert the greatest effect by binding to the microorganism for an extensive length of time.  Penicillin is an example of a time-dependent medication where the goal is to optimize the duration of exposure.

Route

It is also important to consider the route of drug administration within the client’s body. Many of us may have been prescribed oral antibiotics and have simply filled our prescription and completed the drug regimen within the comfort of our own homes. However, there are many types of infections or disease processes that do not respond well to the use of oral antimicrobial therapy. For these diseases, clients may require intravenous or intramuscular injections. Clients requiring intravenous or intramuscular injections may need to be hospitalized, have home health nursing arranged, or travel to the hospital/clinic for their therapy. Concerns with treatment compliance exists with all routes of administration.  For more information about considerations regarding routes of administration, refer to Chapter 1 on absorption. See Figure 3.7 for an illustration of three common routes of medication within the body.

Figure 3.5b Common routes of medication administration include oral, inhalation, and IV

Drug Interactions

For the optimum treatment of select infections, two antibacterial drugs may be administered together. Concurrent drug administration produces a synergistic interaction that is better than the efficacy of either drug alone. In this case, TWO is truly better than ONE! A classic example of synergistic drug combinations is trimethoprim and sulfamethoxazole (Bactrim). Individually, these two drugs provide only bacteriostatic inhibition of bacterial growth, but combined, the drugs are bactericidal.

Although synergistic drug interactions provide a benefit to the client, antagonistic interactions produce harmful effects. Antagonism can occur between two antimicrobials or between antimicrobials and non-antimicrobials being used to treat other conditions. The effects vary depending on the drugs involved, but antagonistic interactions cause diminished drug activity, decreased therapeutic levels due to elevated metabolism and elimination, or increased potential for toxicity due to decreased metabolism and elimination.

Let’s consider an example of these antagonistic interactions.

Many antibacterials are absorbed most effectively from the acidic environment within the stomach. However, if a client takes antacids, the antacids increase the pH of the stomach and negatively impact the absorption of the antibacterial, thus decreasing their effectiveness in treating an infection.

Attributions

• This chapter includes content adapted from Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (© 2022 OpenStax), which is licened under a CC BY 4.0 licence.

Now that we have reviewed antimicrobial basics, common bacterial infections and the nursing process when administering antimicrobials, and general administration considerations, we will take a closer look at specific antimicrobial classes and administration considerations, therapeutic effects, adverse effects, and specific teaching needed for each class of antimicrobials. Each of the following sections of this chapter is based on a class or subclass of anti-infective medications.  Each section discusses the mechanism of action, specific administration considerations, and common client teaching for this class/subclass of medication.  Each section is then followed by a medication table with a common generic medication and its specific administration considerations, therapeutic effects, and side effects/adverse effects for this medication.

Penicillins

Penicillin was the first antibiotic discovered and its detection came as a bit of an accident. In 1928, Alexander Fleming, a professor of bacteriology at St. Mary’s Hospital in London, discovered penicillin accidentally growing in a petri dish in his lab. The penicillin was the result of mold juice that had grown there inadvertently. Fleming noted that this “mold juice” inhibited the growth of Staphylococcus bacteria that was previously growing in the petri dish. Subsequently, the first antibiotic discovery was made.

Indications for  Use

Penicillins are prescribed to treat a variety of infectious processes such as Streptococcal infections, Pneumococcal infections, and Staphylococcal infections. They are considered broad-spectrum for gram-positive bacteria, but have little effectiveness for gram-negative bacteria. Penicillins may be administered orally, IV, or intramuscularly.

Mechanism of Action

Penicillins are bactericidal and kill bacteria by interfering with the synthesis of proteins needed in their cellular walls. When the bacterial cell wall is impaired, the cell is rapidly broken down and destroyed.

Nursing Considerations Across the Lifespan

Penicillins are considered safe for children, with dosages varying based on pediatric clients’ weight. No dosage adjustment is required for clients with hepatic or renal impairment. Penicillins can be used during pregnancy.

Specific Administration Considerations

In addition to general antimicrobial administration considerations, it is important to monitor clients who receive penicillins for signs of superinfections such as C-diff or yeast infections.  There is also a cross-sensitivity for clients allergic to cephalosporins.  It is important to remember that clients who are prescribed high doses of penicillin may experience significant coagulation abnormalities. Other notable drug interactions include the use of diuretic therapy with penicillin. Penicillin contains a significant amount of potassium. Clients receiving potassium-sparing diuretics or supplementation should be monitored for signs of hyperkalemia. Penicillin is best absorbed on an empty stomach; however, many clients may experience GI upset and subsequently take the medication with food.

Client Teaching & Education

The client should notify the health care provider (HCP) if fever or diarrhoea develops, especially if the stool contains blood, pus, or mucus.  Advise the client not to treat diarrhoea without advice from HCP. If GI upset occurs, the client may take the medication with meals but should avoid taking with citrus-based products, which can impede absorption.  Additionally, clients should be instructed to chew oral chewable tablets thoroughly before swallowing.  The client should report a rash or any signs of superinfection (black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stool).

Clients should be instructed to take medication around the clock and to finish the drug completely as directed.  Doses should be spaced evenly to achieve the desired therapeutic effect.  Additionally, clients should receive instruction to not share medication and that any sharing of medications may be dangerous.  Clients with a history of rheumatic heart disease or valve replacement should receive instruction regarding the importance of using antimicrobial prophylaxis before invasive medical or dental procedures. Female clients taking oral contraceptives should use an alternative form of contraception during therapy with amoxicillin and until their next period.  Clients should notify their HCP if symptoms do not improve.

Penecillin Medication Card

Now let’s take a closer look at the penicillin medication card.

Medication grids are intended to assist students to learn key points about each medication.  Basic information related to a common generic medication in this class is outlined, including administration considerations, therapeutic effects, and side effects/adverse effects. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication. Prototype/generic medications listed in the medication card are also hyperlinked directly to a free resource from the United States National Library of Medicine called Daily Med. Other resources you can access for free for evidence-based medication information include: OpenMD and Merck Manuals. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Note: All drug cards are available in the Medication Cards Chapter as editable and printable documents.

Attributions

• Penicillin’s “Mechanism of Action” was adapted from Principles of Pharmacology by Carl Rosow, David Standaert, and Gary Strichartz (republished by LibreTexts), which is licened under a CC BY-NC-SA 4.0 licence.

Cephalosporins are a slightly modified chemical “twin” to penicillins due to their beta-lactam chemical structure. (See Figure 3.7 for a comparison of the beta-lactam ring structure, spectrum of activity, and route of administration across different classes of medications.) Because of these similarities, some clients who have allergies to penicillins may experience cross-sensitivity to cephalosporins.

Figure 3.7 Comparison of beta-lactam ring structure across different classes of medications, spectrum of activity and routes of administration. [Image Description]

Indications for Use: Cephalosporins are used to treat skin and skin-structure infections, bone infections, genitourinary infections, otitis media, and community-acquired respiratory tract infections.

Mechanism of Action: Cephalosporins are typically bactericidal and are similar to penicillin in their action within the cell wall. Cephalosporins are sometimes grouped into “generations” by their antimicrobial properties. The 1st-generation drugs are effective mainly against gram-positive organisms. Higher generations generally have expanded spectra against aerobic gram-negative bacilli. The 5th-generation cephalosporins are active against methicillin-resistant Staphylococcus aureus (MRSA) or other complicated infections.

Nursing Considerations Across the Lifespan:  Most cephalosporins are considered safe for use in pediatrics. Some dose adjustments are required based on renal dysfunction in older adults. Cephalosporins can be given during pregnancy.

Specific Administration Considerations: Clients who are allergic to pencillins may also be allergic to cephalosporins. Clients who consume cephalosporins while drinking alcoholic beverages may experience disulfiram-like reactions including severe headache, flushing, nausea, vomiting, etc.Additionally, like penicillins, cephalosporins may interfere with coagulability and increase a client’s risk of bleeding. Cephalosporin dosing may require adjustment for clients experiencing renal impairment. Blood urea nitrogen (BUN) and creatinine should be monitored carefully to identify signs of nephrotoxicity.

Client Teaching & Education: Clients who are prescribed cephalosporins should be specifically cautioned about a disulfiram reaction, which can occur when alcohol is ingested while taking the medication.  Additionally, individuals should be instructed to monitor for rash and signs of superinfection (such as black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stool) and report to the prescribing provider.

It is also important to note that cephalosporin can enter breastmilk and may alter bowel flora of the infant. Thus, use during breastfeeding is often discouraged.

Cephalosporin Medication Card

Now let’s take a closer look at the cephalosporin medication card. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Note: All drug cards are available in the Medication Cards Chapter as editable and printable documents.

Image Description

Figure 3.7 Comparison of beta-lactam ring structure across different classes of medications, spectrum of activity and routes of administration: Diagrams showing the chemical structures of various medication classes. These medications are:

• Penicillin.
• Cephalosporin.
• Monobactam.
• Carbapenem.

Each of these medications has a becta-lactam ring at the centre.

[Return to Figure 3.7]

Carbapenems are a beta-lactam “cousin” to penicillins and cephalosporins.

Indications for Use: Carbapenems are useful for treating life-threatening, multidrug-resistant infections due to their broad spectrum of activity. These antibiotics are effective in treating gram-positive and gram-negative infections. Because of their broad spectrum of activity, these medications can be especially useful for treating complex hospital-acquired infections or for clients who are immunocompromised.

Mechanism of Action: Carbapenems are typically bactericidal and work by inhibiting the synthesis of the bacterial cell wall.

Nursing Considerations Across the Lifespan:  Some carbapenems (eg. meropenem) are considered safe for use in pediatrics. Dose adjustments are required based on renal dysfunction in older adults. Information related to carbapenems in pregnancy is limited.

Specific Administration Considerations: Carbapenems are similar to cephalosporins.  Cross sensitivity may occur in clients allergic to pencillin or cephalosporins.

Client Teaching & Education:  Clients should monitor for signs of superinfection and report any occurrence to the provider.  If a client experiences fever and bloody diarrhoea, they should contact the provider immediately.  The client should also be advised that side effects can occur even weeks after the medication is discontinued.

Carbapenems Medication Card

Now let’s take a closer look at the medication card for Carbapenems. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Like penicillins, cephalosporins, and carbapenems, monobactams also have a beta-lactam ring structure.

Indications for Use: Monobactams are narrow-spectrum antibacterial medications that are used primarily to treat gram-negative bacteria such as Pseudomonas aeruginosa.

Mechanism of Action: Monobactams are bactericidal and work to inhibit bacterial cell wall synthesis.

Nursing Considerations Across the Lifespan:  Monobactams are considered safe for use in pediatrics. Some dose adjustments are required based on renal dysfunction in older adults. Monobactams can be given during pregnancy if the client is allergic to other, more preferred, antibiotics.

Specific Administration Considerations: Clients taking monobactams may experience adverse effects similar to other beta-lactam medications, so nurses should monitor for GI symptoms, skin sensitivities, and coagulation abnormalities.

Client Teaching & Education: Clients should monitor for signs of superinfection and report any occurrence to the provider. If the client experiences fever and bloody diarrhea, they should contact the provider immediately.  The client should also be advised to notify the provider immediately if symptoms progress or if any sign of allergic response occurs. 

Monobactams Medication Card

Now let’s take a closer look at the medication card for Monobactams. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Sulfonamides are one of the oldest broad-spectrum antimicrobial agents that work by competitively inhibiting bacterial metabolic enzymes needed for bacterial function.

Indications for Use: Sulfonamides are used to treat urinary tract infections, otitis media, acute exacerbations of chronic bronchitis, and travelers’ diarrhea.

Mechanism of Action: This mechanism of action provides bacteriostatic inhibition of growth against a wide spectrum of gram-positive and gram-negative pathogens.

Nursing Considerations Across the Lifespan: Sulfonamides are safe for use in pregnancy and with paediatric clients. Dosing should be altered for any client with renal insufficiency.

Specific Administration Considerations: Allergic reactions to sulfonamide medications are common and, therefore, clients should be monitored carefully for adverse effects including delayed hypersensitivity reactions. Sulfonamide medications increase the risk of crystalluria that can cause kidney stones or decreased kidney function; therefore, clients should increase their water intake while taking these medications.

Client Teaching & Education: The client should receive education to complete the full prescribed dose of medications and take measures to not skip doses.  If a dose is missed, the client should take the missed dose as soon as possible unless it is near the next dosing time.  The medication can cause increased photosensitivity, and clients should be educated to use sunscreen and protective clothing with sun exposure.  The client should also report any rash, sore throat, fever, or mouth sores that might occur.  Unusual bleeding or bruising should also be reported to the provider.  If clients are receiving prolonged therapy, they may require platelet count monitoring.

Sulfonamides Medication Card

Now let’s take a closer look at the medication card for trimethoprim-sulfamethoxazole. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Indications for Use: Fluoroquinolones may be used to treat pneumonia or complicated skin or urinary tract infections.

Mechanism of Action: Fluoroquinolones are a synthetic antibacterial medication that work by inhibiting the bacterial DNA replication. They are bacteriocidal due to the action they take against the DNA of the bacterial cell wall. Many fluoroquinolones are broad spectrum and effective against a wide variety of both gram-positive and gram-negative bacteria.

Nursing Considerations Across the Lifespan:  Fluoroquinolones are safe to use in pediatrics and with older adults.  Dose adjustments are required for renal insufficiency.  There is limited data on safety in pregnancy.

Specific Administration Considerations: Clients taking oral fluoroquinolones should avoid the use of antacid medication as antacids significantly impede absorption. Clients should also be instructed to take oral fluoroquinolones with a full glass of water two hours before or after meals to enhance absorption and prevent crystalluria. Fluoroquinolone therapy is contraindicated in children except for complicated UTIs, pyelonephritis, plague, or post Anthrax exposure and should be used cautiously in pregnancy.

Black Box Warning:  Black Box Warnings are the strongest warnings issued by the Federal Drug Association (FDA) (equivalent to “Safety Warnings” by Health Canada) and signify that the medical studies have indicated that the drug carries a significant risk of serious or life-threatening adverse effects.

Fluoroquinolones, including, have been associated with disabling and potentially irreversible serious adverse reactions, including:

• Tendinitis and tendon rupture
• Peripheral neuropathy
• Central nervous system effects
• Exacerbation of muscle weakness in clients with myasthenia gravis

In clients who experience any of these serious adverse reactions, discontinue the medication immediately, and avoid the use of fluoroquinolones.

Client Teaching & Education: All clients on fluoroquinolone therapy should be instructed to avoid direct and indirect sunlight due to the photosensitivity that can be experienced while on these medications.  The client should take measures to ensure that dosages are spaced evenly throughout the day and that fluid balance is maintained.  It is important to maintain an intake of 1500mL-2000mL per day while taking the medication.  The client should be advised that medications containing calcium, aluminum, iron, or zinc may impair absorption and should be avoided. Other side effects of fluoroquinolones increase drowsiness.  Additionally, the client should be cautioned to monitor for episodes of fainting or decreased heart rate and report any history of prolonged QT syndrome.  If a client notices peripheral neuropathy occurring, this should be reported to the healthcare provider.  Additional side effects to monitor include increased tendon pain, jaundice, rash, or mood changes.

Flouroquinolones Medication Card

Now let’s take a closer look at the medication card for levofloxacin. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review recommendations before administering specific medication.

Macrolides are complex antibacterial broad-spectrum medications that are effective against both gram-positive and gram-negative bacteria.

Mechanism of Action: Macrolides inhibit RNA protein synthesis and suppress reproduction of the bacteria. Macrolides are bacteriostatic as they do not actually kill bacteria, but inhibit additional growth and allow the body’s immune system to kill the offending bacteria.

Indications for Use: Macrolides are often used for respiratory infections, otitis media, pelvic inflammatory infections, and Chlamydia.

Nursing Considerations Across the Lifespan: Macrolides are safe for use across the lifespan, including in pregnancy and with pediatric clients.

Specific Administration Considerations: Macrolides can have significant impact on liver function and should be used cautiously in clients with liver disease or impairment.

Patient Teaching & Education: GI upset is common and clients can be advised to take medication with food. Clients should also be advised to avoid excessive sunlight and to wear protective clothing and use sunscreen when outside, as well as to report any adverse reactions immediately.  Advise clients to report symptoms of chest pain, palpitations, or yellowing of eyes or skin.  Additionally, clients should be advised that these medications can cause drowsiness.

Macrolides Medication Card

Now let’s take a closer look at the medication card for erythromycin and azithromycin. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Aminoglycosides are potent broad-spectrum antibiotics that are useful for treating severe infections. Many aminoglycosides are poorly absorbed in the GI tract; therefore, the majority are given IV or IM. Aminoglycosides are potentially nephrotoxic and neurotoxic. They should be administered cautiously. Blood peak and trough levels should be performed to titrate a safe dose for each client.

Indications for Use: Streptomycin is used for streptococcal endocarditis and a second line treatment for tuberculosis. Neomycin is used in the treatment of hepatic encephalopathy as adjunct therapy to lower ammonia levels and is also used as a bowel prep for colon procedures.

Mechanism of Action: Aminoglycosides are bactericidal and bind with the area of the ribosome known as the 30S subunit, inhibiting protein synthesis in the cell wall and resulting in bacterial death (see Figure 3.13). Aminoglycosides may be given with beta-lactam medications to facilitate transport of aminoglycoside across the cellular membrane, resulting in a synergistic effect and increasing drug effectiveness.

Figure 3.13 Medications that inhibit protein synthesis [Image Description]

Nursing Considerations Across the Lifespan:  Aminoglycosides are safe to use in pediatric clients, with dose adjustments made based on the client’s weight.  Some aminoglycosides are not safe for use in pregnancy, as they can cause fetal harm. In adult and older adult populations, renal function should be assessed as dose adjustments may be required.

Special Administration Considerations: Aminoglycosides can result in many adverse effects for the client and, therefore, the nurse should monitor the client carefully for signs of emerging concerns. Peak and trough levels are used to titrate this medication to a safe dose. Aminoglycosides can be nephrotoxic (damaging to kidney), neurotoxic (damaging to the nervous system), and ototoxic (damaging to the ear). Nurses should monitor the client receiving aminoglycosides for signs of decreased renal function such as declining urine output and increasing blood urea nitrogen (BUN), creatinine, and declining glomerular filtration rate (GFR). Indications of damage to the neurological system may be assessed as increasing peripheral numbness or tingling in the extremities. Additionally, the client should be carefully assessed for hearing loss or hearing changes throughout the course of drug administration.

ClientTeaching & Education: Clients receiving aminoglycosides should be advised to monitor for signs of hypersensitivity and auditory changes.  This may include tinnitus and hearing loss.  Clients may also experience accompanying vertigo while on the medication.  Clients should be advised to drink plenty of fluids while taking the medication.  Female clients should notify their provider if pregnancy is planned or if they are actively breastfeeding.

Streptomycin and Gentamycin Medication Card

Now let’s take a closer look at the medication card for streptomycin and gentamycin. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Image Description

Figure 3.13 Medications that inhibit protein synthesis: Diagram of a cell undergoing protein synthesis that describes the major classes of protein synthesis–inhibiting antibacterials. These include:

• Chloramphenicol, macrolides, and lincosamides, which:
  • Bind to the 50S ribosomal subunit
  • Prevent peptide bond formation
  • Stop protein synthesis
• Aminoglycosides, which:
  • Bind to the 30S ribosomal subunit
  • Impair proofreading, resulting in production of faulty proteins
• Tetracyclines, which:
  • Bind to the 30S ribosomal subunit
  • Block the binding of tRNAs, thereby inhibiting protein synthesis

[Return to Figure 3.13]

Tetracyclines are broad-spectrum antibiotics that are bacteriostatic, subsequently inhibiting bacterial growth.

Indications for Use: Tetracycline medications are useful for the treatment of many gram-positive and gram-negative infectious processes, yet are limited due to the significance of side effects experienced by many clients.

Mechanism of Action: Tetracyclines work by penetrating the bacterial cell wall and binding to the 30S ribosome, inhibiting the protein synthesis required to make the cellular wall.

Nursing Considerations Across the Lifespan: Tetracyclines are contraindicated in pregnancy and for children ages 8 and under. Small amounts may be excreted in breast milk. For adults and older adults, dose adjustments need to be made for renal impairment.

Special Administration Considerations: Significant side effects of tetracycline drug therapy include photosensitivity, discolouration of developing teeth and enamel hypoplasia, and renal and liver impairment.

Client Teaching & Education: Clients should be instructed to avoid direct sunlight exposure and wear sunscreen to prevent skin sensitivities. Additionally, it is important for clients to be educated regarding potential impaired absorption of tetracycline with the use of dairy products.  Clients who are on oral contraceptives should be educated that tetracyclines may impede the effectiveness of the oral contraceptive and an alternative measure of birth control should be utilized while on the antibiotic. Female clients must be aware to immediately stop tetracycline if they become pregnant.  Expired tetracycline should be immediately disposed of as it can become toxic.

Tetracycline Medication Card

Now let’s take a closer look at the medication card for tetracycline. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Figure 3.15a Images of viruses (a) Members of the Coronavirus family can cause respiratory infections like the common cold, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). Here they are viewed under a transmission electron microscope (TEM). (b) Ebolavirus, a member of the Filovirus family. (credit a: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by Thomas W. Geisbert)

Unlike the complex structure of fungi or protozoa, viral structure is simple.  There are several subclasses of antiviral medications: antiherpes, antiinfluenza, anti-hepatitis, and antiretrovirals.  Each subclass will be discussed in more detail below.  See Figure 3.10 for images of viruses.

Subclass: Antiherpes

Indications for Use: Acyclovir (Zovirax) and its derivatives are frequently used for the treatment of herpes and varicella virus infections, including genital herpes, chickenpox, shingles, Epstein-Barr virus infections, and cytomegalovirus infections.

Mechanism of Action: Acyclovir causes termination of the DNA chain during the viral replication process. Acyclovir can be administered either topically or systemically, depending on the infection.

Special Administration Considerations: Acyclovir use may result in nephrotoxicity.

Client Teaching & Education: Clients who are being treated with antiviral therapy should be instructed about the importance of medication compliance. They may also experience significant fatigue, so periods of rest should be encouraged.

Subclass: AntiInfluenza

Indications for Use: Tamiflu (oseltamivir) is used to target the influenza virus by blocking the release of the virus from the infected cells.

Mechanism of Action: Tamiflu prevents the release of virus from infected cells.

Special Administration Considerations: This medication does not cure influenza, but can decrease flu symptoms and shorten the duration of illness if taken in a timely manner. Ckients are prescribed the medication for prophylaxis against infection, known exposure, or to lesson the course of the illness. If clients experience flu-like symptoms, it is critical that they start treatment within 48 hours of symptom onset.

Client Teaching & Education: Clients who are being treated with antiviral therapy should be instructed about the importance of medication compliance. They may also experience significant fatigue, so periods of rest should be encouraged.

The influenza virus is one of the few RNA viruses that replicates in the nucleus of cells. Antivirals block the release stage. See Figure 3.11.

Figure 3.15b Influenza virus replication stages

Subclass: Antiretrovirals

Viruses with complex life cycles, such as HIV, can be more difficult to treat. These types of viruses require the use of antiretroviral medications that block viral replication. (See Figure 3.12 to view the viral replication process of HIV.) Additionally, antiretrovirals fall under the class of antiviral medications.

Figure 3.15c HIV attaches to a cell surface receptor of an immune cell and fuses with the cell membrane. Viral contents are released into the cell, where viral enzymes convert the single-stranded RNA genome into DNA and incorporate it into the host genome

Indications for Use: Antiretrovirals are used for the treatment of illnesses like HIV.

Mechanism of Action: Antiretrovirals impede virus replication.

Special Administration Considerations:  Many antiretrovirals may impact renal function; therefore, the client’s urine output and renal labs should be monitored carefully for signs of decreased function.

Client Teaching & Education: Clients who are being treated with antiviral therapy should be instructed about the importance of antiretroviral compliance. They may also experience significant fatigue, so periods of rest should be encouraged.

Acyclovir Medication Card

Now let’s take a closer look at the medication cards for the subclasses of antivirals. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Figure 3.16 Candida albicans is a unicellular fungus, or yeast. It is the causative agent of vaginal yeast infections as well as oral thrush, a yeast infection of the mouth that commonly afflicts infants.

Fungi are important to humans in a variety of ways. Both microscopic and macroscopic fungi have medical relevance, but some pathogenic species that can cause mycoses (illnesses caused by fungi). See Figure 3.13 for a microscopic image of candida albicans that is the causative agent of yeast infections. Some pathogenic fungi are opportunistic, meaning that they mainly cause infections when the host’s immune defenses are compromised and do not normally cause illness in healthy individuals. Fungi are important in other ways. They act as decomposers in the environment, and they are critical for the production of certain foods such as cheeses. Fungi are also major sources of antibiotics, such as penicillin from the fungus Penicillium..

Indications:

Imidazoles are synthetic fungicides commonly used in medical applications and also in agriculture to keep seeds and harvested crops from molding. Examples include miconazole, ketoconazole, and clotrimazole, which are used to treat fungal skin infections such as ringworm, specifically tinea pedis (athlete’s foot), tinea cruris (jock itch), and tinea corporis.

Triazole drugs, including fluconazole, can be administered orally or intravenously for the treatment of several types of systemic yeast infections, including oral thrush and cryptococcal meningitis, both of which are prevalent in clients with AIDS. Triazoles also exhibit more selective toxicity, compared with the imidazoles, and are associated with fewer side effects.

Allylamines, a structurally different class of synthetic antifungal drugs, are most commonly used topically for the treatment of dermatophytic skin infections like athlete’s foot, ringworm, and jock itch. Oral treatment with terbinafine is also used for fingernail and toenail fungus, but it can be associated with the rare side effect of hepatotoxicity.

Polyenes are a class of antifungal agents naturally produced by certain actinomycete soil bacteria and are structurally related to macrolides. Common examples include nystatin and amphotericin B. Nystatin is typically used as a topical treatment for yeast infections of the skin, mouth, and vagina, but may also be used for intestinal fungal infections. The drug amphotericin B is used for systemic fungal infections like aspergillosis, cryptococcal meningitis, histoplasmosis, blastomycosis, and candidiasis. Amphotericin B was the only antifungal drug available for several decades, but its use has associated serious side effects, including nephrotoxicity.

Mechanism of Action: Antifungals disrupt ergosterol biosyntheses of the cell membrane increasing cellular permeability and causing cell death.

Special Administration Considerations: Administration guidelines will vary depending on the type of fungal infection being treated. It is important to monitor response of the affected area and examine class-specific administration considerations to monitor client response.

Client Teaching & Education: The client should be advised to follow dosage instructions carefully and finish the drug completely, even if they feel their symptoms have resolved.  The client should report any skin rash, abdominal pain, fever, or diarrhea to the provider.  The client should monitor carefully for unexplained bruising or bleeding, which may be a sign of liver dysfunction.

Antifungal Medication Card

Now let’s take a closer look at the medication card for various antifungals in Table 3.15.

Malaria is a prevalent protozoal disease impacting individuals across the world. According to the Centers for Disease Control, approximately 450 cases of malaria are diagnosed in Canada each year.

Indications for Use: Antimalarials are used for the prevention or treatment of malaria.

Mechanism of Action: Antimalarial agents work by targeting specific intracellular processes that impact cell development.

Nursing Considerations across the Lifespan: Antimalarial agents are safe to use for all age groups.  Dose adjustments are not needed for renal or liver dysfunction.

Special Administration Considerations: Antimalarial medications may impact hearing and vision so clients should be monitored carefully for adverse effects. Additionally, antimalarial medications may cause GI upset, so clients should be instructed to take these medications with food.

Client Teaching & Education: Clients should receive instruction to take medication as prescribed and adhere to the full prescription regimen.  Clients should minimize additional exposure to mosquitoes using preventative means such as repellents, protective clothing, netting, etc.  Clients on chloroquine therapy should also avoid alcohol.  Chloroquine can be extremely toxic to children and should be safely stored and out of reach.  Clients receiving antimalarial therapy may have increased sensitivity to light and should be counseled to wear protective glasses to prevent ocular damage.  Treatment often requires sustained regimens of six months or greater so clients should be monitored carefully for adherence and compliance.

Chloroquine Medication Card

Now let’s take a closer look at the medication card on chloroquine. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Figure 3.18 Giardia lamblia

Antiprotozoal drugs target infectious protozoans such as Giardia, an intestinal protozoan parasite that infects humans and other mammals, causing severe diarrhea (see Figure 3.14 for a microscopic image of Giardia).

Indications:  Metronidazole is an example of an antiprotozoal antibacterial medication gel that is commonly used to treat acne rosacea, bacterial vaginosis, or trichomonas. Metronidazole IV is used to treat Giardia and also serious anaerobic bacterial infections such as Clostridium difficile (C-diff).

Mechanism of Action: Many antiprotozoal agents work to inhibit protozoan folic acid synthesis, subsequently impairing the protozoal cell.

Special Administration Considerations: It can be administered PO, parenterally, or topically. Orally is the preferred route for GI infections. The nurse should monitor the client carefully for side effects such as seizures, peripheral neuropathies, and dizziness. Psychotic reactions have been reported with alcoholic clients taking disulfiram.

Client Teaching & Education

Clients taking antiprotozoal medications should receive education regarding the need for medication compliance and prevention of reinfection.  They should be advised that the medication may cause dizziness and dry mouth.  Additionally, the medication may cause darkening of the urine.  They should also avoid alcoholic beverages during medication therapy to prevent a disulfiram-like reaction.

If clients are being treated for protozoal infections such as trichomoniasis, they should be advised that sexual partners might be sources of reinfection even if asymptomatic.  Partners should also receive treatment.

Client teaching should include the avoidance of alcohol during therapy.

There are two major groups of parasitic helminths: the roundworms (Nematoda) and flatworms (Platyhelminthes). See Figure 3.19 for images of a tapeworm and a guinea worm. Of the many species that exist in these groups, about half are parasitic and some are important human pathogens.

Indications: Anthelmintic medications target parasitic helminths.

Mechanism of Action: Because helminths are multicellular eukaryotes like humans, developing drugs with selective toxicity against them is extremely challenging. Despite this, several effective classes have been developed. Many anthelmintic medications work by preventing microtubule formation within the parasitic cell, compromising glucose uptake. Others work by blocking neuronal transmission within the parasite, subsequently causing starvation, paralysis, and death of the worms. Additionally, many antihelminths inhibit ATP formation and impair calcium uptake inducing paralysis and death of the worms.

Special Administration Considerations: Prolonged therapy using antihelmintic medication can result in liver damage and bone marrow suppression.

Client Teaching & Education: Clients on antihelmintic drug therapy should receive special instruction to ensure rigorous hygienic precautions to minimize the risk of reinfection.  They should also wash all bedding, linens, towels, and clothing following treatment to minimize reinfection risk.

Figure 3.19.  A) The tapeworm Taenia saginata, that infects both cattle and humans. Eggs are microscopic, but the adult tapeworm like the one show here can reach 4-10 meters, taking up residence in the digestive system. B) An adult guinea worm, Dracunculus medinensis, is removed through a lesion in the patient’s skin by winding it around a matchstick

M. tuberculosis is the causative agent of tuberculosis (TB), a disease that primarily impacts the lungs but can infect other parts of the body as well. It has been estimated that one third of the world’s population has been infected with M. tuberculosis and millions of new infections occur each year. Treatment of M. tuberculosis is challenging and requires clients to take a combination of drugs for an extended time. Complicating treatment even further is the development and spread of multidrug-resistant strains of this pathogen.

Indications for Use: Antitubercular medications are selective for mycobacteria work by inhibiting growth or selectively destroying mycobacteria.

Mechanism of Action: They work impacting the synthesis or transcription of mycobacteria RNA or inhibiting the synthesis of mycolic acids in the cellular wall. Mycobacteria can develop resistance to antitubercular medications; therefore, strict compliance to drug regimen must be emphasized.

Special Administration Considerations:  Antitubicular medications require at least six months of treatment. Many antitubercular medications may impact liver function, and liver enzymes should be monitored carefully. Other side effects to medication administration include GI symptoms, peripheral neuropathy, and vision changes.

Client Teaching/Education: Advise clients that medications must be taken as directed.  It is important that clients understand the significance of continuing drug therapy even after symptoms have resolved to prevent the spread of disease.  Drug therapy may be continued for six months to two years.  If a client notices any change in visual acuity or eye discomfort, it should be reported immediately to the healthcare provider.

Clients should also be advised to avoid alcohol during antitubercular therapy because of the increased risk of liver toxicity.  Foods containing tyramine such as tuna and Swiss cheese should be avoided.

Vancomycin is a glycopeptide commonly used to treat MRSA.

Indications for Use: Vancomycin is a popular glycopeptide that is active against gram-positive bacteria. Vancomycin is commonly used to treat serious or severe infections when other antibiotics are ineffective or contraindicated, including those caused by MRSA.

Mechanism of Action: Glycopeptides are a class of medications that inhibit bacterial cell wall synthesis.

Special Administration Considerations: It is poorly absorbed from the GI tract, so it must be given by IV to treat a systemic infection. Oral vancomycin, on the other hand, is used to treat antibiotic-associated clostridium difficile (C-diff). Vancomycin poses a significant risk to kidney function and hearing; therefore, clients’ trough levels must be monitored carefully for effective IV dosing to avoid complications. Clients receiving IV vancomycin may also experience a complication known as “red man syndrome” in which they experience a flushing of the skin and a reddish rash on the upper body when the infusion is administered too rapidly.

Client Teaching/Education: Clients should be counselled to take medications as directed for the full course of antibacterial therapy.  They should monitor for side effects such as hypersensitivity, tinnitus, hearing loss, and vertigo.  Clients should promptly follow up with their healthcare provider if no improvement in symptoms is identified.

Vancomycin Medication Card

Now let’s take a closer look at the medication card on vancomycin. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Now that you’ve learned all about antimicrobials, practice applying your knowledge with the following activities.

Antagonistic Interactions: Concurrent administration of two drugs causes harmful effects such as a decrease of drug activity, decreased therapeutic levels due to increased metabolism and elimination, or increased potential for toxicity due to decreased metabolism and elimination.  An example of an antagonistic interaction is taking antacids with antibiotics, causing decreased absorption of the antibiotic.

Antifungal: Medications that are used to treat fungal infections.  For example, nystatin is used to treat Candida Albicans, a fungal infection.

Antiviral: Medications used to treat viral infections. For example, Tamiflu is used to treat influenza.

Bactericidal: Antimicrobial drugs that kill their target bacteria.

Bacteriostatic: Antimicrobial drugs that cause bacteria to stop reproducing but may not ultimately kill the bacteria.

Black Box Warnings: The strongest warnings issued by the Federal Drug Administration (FDA) that signify the drug carries a significant risk of serious or life-threatening adverse effects.

Broad-Spectrum Antimicrobial: An antibiotic that targets a wide variety of bacterial pathogens, including both gram-positive and gram-negative species.

Clostridium Difficile (C-diff): Clostridium difficile causes pseudomembranous colitis, a superinfection that can be caused by broad spectrum antibiotic therapy.

Culture: A test performed on various body substances for the presence of bacteria or fungus.

Dose-Dependent: A more significant response occurs in the body when the medication is administered in large doses to provide a large amount of medication to the site of infection for a short period of time.

Gram-Positive: Gram-positive bacteria are classified by the color they turn after a chemical called Gram stain is applied to them. Infections caused by Streptococcus and Staphylococcus bacteria are examples of gram-positive infections.

Gram-Negative:  Gram-negative bacteria are classified by the color they turn after a chemical called Gram stain is applied to them. Escherichia Coli (also known as E. Coli) is an example of a gram-negative infection.

Gram Stain: A test used to quickly diagnose types of bacterial infection. Gram-positive and gram-negative bacteria stain differently because their cell walls are different. Identification of bacteria as gram-positive or gram-negative assists the healthcare provider in selecting an appropriate antibiotic to treat the infection.

Half-Life: The rate at which 50% of a drug is eliminated from the bloodstream.

Indications: The use of a drug for treating a particular condition or disease.  The FDA determines if there is enough evidence for a labeled indication of a drug. Providers may also prescribe medications for off-label indications if there is reasonable scientific evidence that the drug is effective, but these uses have not been approved by the FDA.

Mechanism of Action:  The way in which a drug affects microbes at the cellular level.

Methicillin-Resistant S. Aureus (MRSA):  An infection caused by Methicillin-resistant Staphylococcus aureus that is difficult to treat because it exhibits resistance to nearly all available antibiotics.

Narrow-Spectrum Antimicrobial: An antibiotic that targets only specific subsets of bacterial pathogens.

Pathogen: An organism causing disease to its host.

Prototype: A common individual drug that represents a drug class or group of medications having similar chemical structures, mechanism of actions, and modes of action.

Resistance: A characteristic of bacteria manifested when sensitivity analysis is performed, demonstrating lack of effective treatment by a particular antibiotic.

Sensitivity Analysis: A test performed in addition to a culture to select an effective antibiotic to treat a microorganism.

Superinfection: A secondary infection in a patient having a preexisting infection.  C-diff and yeast infections resulting from antibiotic therapy are examples of superinfections.

Synergistic Interaction: Concurrent drug administration producing a synergistic interaction that is better than the efficacy of either drug alone.  An example of synergistic drug combinations is trimethoprim and sulfamethoxazole (Bactrim).

Time Dependent: Time dependency occurs when greater therapeutic effects are seen with lower blood levels over a longer period of time.

Vancomycin-Resistant S. Aureus (VRSA): An infection caused by Vancomycin-resistant Staphylococcus aureus that is difficult to treat because it exhibits resistance to nearly all available antibiotics.

Have you ever wondered what causes your heart to beat or your lungs to breathe? These are examples of involuntary responses the brain controls without the need for conscious thought. The autonomic nervous system (ANS) works using a balance of the sympathetic and parasympathetic nervous systems that regulate the body’s involuntary functions, including heart rate, respiratory rate, digestion, and sweating. Many medications are used to control various cardiovascular, respiratory, and gastrointestinal conditions by acting on ANS receptors. Beta-blockers and anticholinergic medications are the most commonly prescribed medications in this category.

This section will review key anatomy concepts in the autonomic nervous system (ANS) related to the mechanism of action of medications. For more detailed information regarding the concepts reviewed, use the links provided to review detailed autonomic nervous system content in the Open Stax Anatomy and Physiology book:

Review the basic structure and function of the nervous system.

Review the anatomy of sensory perception.

Review the anatomy of motor responses.

Review the divisions of the autonomic nervous system.

Review autonomic reflexes and homeostasis.

Review information on a few drugs that affect the autonomic nervous system.

Components and Functions of the Nervous System

Figure 4.2a Central and Peripheral Nervous System

The nervous system has two major components: the central nervous system (CNS) and the peripheral nervous system. See Figure 4.2a. The central nervous system (CNS) is composed of the brain and the spinal cord. The peripheral nervous system includes nerves outside the brain and spinal cord and consists of sensory neurons and motor neurons. Sensory neurons sense the environment and conduct signals to the brain that become a conscious perception of that stimulus. This conscious perception may lead to a motor response that is conducted from the brain to the peripheral nervous system via motor neurons to cause a movement. Motor neurons consist of the somatic nervous system that stimulates voluntary movement of muscles and the autonomic nervous system that controls involuntary responses. This chapter will focus on the autonomic nervous system.

The two divisions of the autonomic nervous system are the sympathetic division (SNS) and the parasympathetic division (PNS). The SNS contains alpha and beta receptors, and the PNS contains nicotinic and muscarinic receptors. Each type of receptor has a specific action when stimulated (see Figure 4.2b for an image of the divisions of the nervous system and the receptors in the ANS).

Figure 4.2b Components of the Nervous System and ANS receptors [Image Description]

SNS and PNS Functions and Homeostasis

The sympathetic system is associated with the "fight-or-flight" response, and parasympathetic activity is often referred to as “rest and digest.” See Figure 4.2c to compare the effects on PNS and SNS stimulation on target organs.  The autonomic nervous system regulates many of the internal organs through a balance of these two divisions and is instrumental in homeostatic mechanisms in the body.

Figure 4.2c Effects of PNS and SNS Stimulation on Target Organs

Stimulation of SNS primarily produces increased heart rate, increased blood pressure via the constriction of blood vessels, and bronchial dilation. In comparison, stimulation of the PNS causes slowing of the heart, lowering of blood pressure due to vasodilation, bronchial constriction, and focuses on stimulating intestinal motility, salivation, and relaxation of the bladder.

Homeostasis is the balance between the two systems. At each target organ, dual innervation determines activity. For example, the heart receives connections from both the sympathetic and parasympathetic divisions. SNS stimulation causes the heart rate to increase, whereas PNS stimulation causes the heart rate to decrease.

To respond to a threat – to “fight or flight” – the sympathetic system stimulates many different target organs to achieve this purpose. For example, if a person sees a grizzly bear in the wilderness, the individual has the choice to stand and fight the bear or to run away. For either choice, several things must occur for additional oxygen and glucose to be delivered to skeletal muscle to fight or run. The respiratory, cardiovascular, and musculoskeletal systems are all activated to breathe rapidly, cause bronchodilation in the lungs to inhale more oxygen, stimulate the heart to pump more blood, and increase blood pressure to deliver it to the muscles. The liver creates more glucose for energy for the muscles to use. The pupils dilate to see the threat (or the escape route) more clearly. Sweating prevents the body from overheating from excess muscle contraction.  Since the digestive system is not needed during this time of threat, the body shunts oxygen-rich blood to the skeletal muscles. To coordinate all these targeted responses, catecholamines such as epinephrine and norepinephrine are released in the sympathetic system and disperse to the many neuroreceptors on the target organs simultaneously.

Chemical Signaling in the Autonomic Nervous System

Figure 4.2d Autonomic System neurons conduct signals via the preganglionic neurons to postganglionic neurons to the target organs. [Image Description]

Neurons conduct impulses to the synapse of a target organ. The synapse is a connection between the neuron and its target cell. See Figures 4.2e and 4.2f for images of synapse connections.

Figure 4.2e The synapse is the connection between a neuron and its target cell where neurotransmitters are released

Preganglionic Neurons

The synapse is composed of a preganglionic (presynaptic) neuron and a postganglionic (postsynaptic) neuron. Preganglionic neurons release acetylcholine (ACh) onto nicotinic receptors on the postganglionic neuron.  Nicotine, found in tobacco products, also binds to and activates nicotinic receptors, mimicking the effects of ACh. This is worth noting, because if medications were developed to impact the nicotinic receptors, then it would impact both the SNS and PNS systems at the preganglionic level. Instead, most medications target the postganglionic neurons, because each type of postganglionic neuron has different neurotransmitters and different target receptors.

Postganglionic Neurons

There are different types of postganglionic neurons in the SNS and PNS branches of the autonomic nervous system. Postganglionic neurons of the PNS branch are classified as cholinergic, meaning that acetylcholine (ACh) is released, whereas postganglionic neurons of the SNS are classifed as adrenergic, meaning that norepinephrine (NE) is released. The terms cholinergic and adrenergic refer not only to the signal that is released, but also to the class of neuroreceptors that each binds. (See Figure 4.2f for an image of the release of ACh and NE and their attachment to the corresponding adrenergic or nicotinic receptors.)

The cholinergic system of the PNS includes two classes of postganglionic neuroreceptors: the nicotinic receptor and the muscarinic receptor. Both receptor types bind to ACh and cause changes in the target cell. The situation is similar to locks and keys. Imagine two locks—one for a classroom and the other for an office—opened by two separate keys. The classroom key will not open the office door, and the office key will not open the classroom door. This is similar to the specificity of nicotine and muscarine for their receptors. However, a master key can open multiple locks, such as a master key for the biology department that opens both the classroom and the office doors. This is similar to ACh that binds to both types of receptors.

The adrenergic system of the SNS has two major types of neuroreceptors: the alpha (α)-adrenergic receptor and beta (β)-adrenergic receptor. There are two types of α-adrenergic receptors, termed α1 and α2, and there are two types of β-adrenergic receptors, termed β1 and β2. An additional aspect of the adrenergic system is that there is a second neurotransmitter in addition to norepinephrine. The second neurotransmitter is called epinephrine. The chemical difference between norepinephrine and epinephrine is the addition of a methyl group (CH3) in epinephrine. The prefix “nor-” actually refers to this chemical difference in which a methyl group is missing.

The term adrenergic should remind you of the word adrenaline, which is associated with the fight-or-flight response described earlier. Adrenaline and epinephrine are two names for the same molecule. The adrenal gland (in Latin, ad- = “on top of”; renal = “kidney”) secretes adrenaline. The ending “-ine” refers to the chemical being derived, or extracted, from the adrenal gland.

Figure 4.2f Sympathetic and Parasympathetic Pre-and Postganglionic Fibers and Neuroreceptors

ANS Neuroreceptors and Effects

The effects of stimulating each type of neuroreceptor are outlined in this section and sample uses of medications are provided.

Sympathetic Nervous System

SNS receptors include Alpha-1, Alpha-2, Beta-1, and Beta-2 receptors. Epinephrine and norepinephrine stimulate these receptors, causing the overall fight-or-flight response in various target organs. Medications causing similar effects are called adrenergic agonists, or sympathomimetics, because they mimic the effects of the body’s natural SNS stimulation. On the other hand, adrenergic antagonists block the effects of the SNS receptors. Dopamine also stimulates these receptors, but it is dosage-based. Dopamine causes vasodilation of arteries in the kidney, heart, and brain, depending on the dosage. See Table 4.2 for a comparison of stimulation and inhibition of these SNS receptors.

Adrenergic Agonists

Adrenergic agonists stimulate Alpha-1, Alpha-2, Beta-1, or Beta-2 receptors. Stimulation of each type of receptor has different effects and are further explained below.

Alpha-1 receptor agonists: Stimulation of Alpha-1 receptors causes vasoconstriction in the periphery, which increases blood pressure. Vasoconstriction also occurs in mucus membranes, which decreases swelling and secretions for patients experiencing upper respiratory infections. Examples of Alpha-1 agonist medications are pseudoephedrine or phenylephrine, used to treat nasal congestion.

Alpha-2 receptor agonists: Stimulation of Alpha-2 receptors reduces CNS stimulation and is primarily used as an antihypertensive or a sedative. An example of an Alpha-2 agonist medication is clonidine, which is used to treat hypertension and is also used to treat attention deficit hyperactivity disorder.

Beta-1 receptor agonists: Stimulation of Beta-1 receptors primarily affects the heart by increasing heart rate and contractility. It also causes the kidneys to release renin. Effects on the heart are described as having a positive chronotropic (increases heart rate), positive inotropic (increases force of contraction), and positive dromotropic (increases speed of conduction between SA and AV node) properties. Medications that stimulate Beta-1 receptors are primarily used during cardiac arrest, acute heart failure, or shock. An example of a Beta-1 receptor agonist medication is dobutamine, which is used to increase cardiac output in someone experiencing acute heart failure or shock. See Figure 4.2g  illustrating dromotropic properties of stimulating Beta-1 receptors.

Figure 4.2g Dromotropic Properties Affect the Speed of Conduction Between SA and AV Nodes

Beta-2 receptor agonists: Stimulation of Beta-2 receptors causes relaxation in smooth muscle in the lungs, GI, uterus, and liver. Medications that stimulate Beta-2 receptors are primarily used to promote bronchodilation, which opens the airway, and are often used to treat patients with asthma or chronic obstructive pulmonary disease (COPD). An example of a Beta-2 receptor agonist medication used in asthma is albuterol. See Figure 4.2h  for an illustration of the effects of stimulating Beta-2 receptors in the lungs.

Side effects of Beta-2 receptor agonists are related to stimulation of Beta-2 receptors in other locations in the body. For example, albuterol can cause tachycardia by stimulating Beta-2 receptors in the heart. Stimulation of Beta-2 receptors can also inadvertently cause hyperglycemia in patients with diabetes because of activation of Beta-2 receptors in the liver, causing glyconeogenesis.

Figure 4.2h Effects of Medications Stimulating Beta 2 Receptors in the Lungs [Image Description]

Adrenergic Antagonists

Adrenergic antagonist medications inhibit the Alpha-1, Alpha-2, Beta-1, and Beta-2 receptors. The effects of inhibition of each receptor are explained further below.

Alpha-1 antagonists: Alpha-1 antagonists are primarily used to relax smooth muscle in the bladder and cause vasodilation.

Examples include:

• Tamsulosin is used to decrease resistance of an enlarged prostate gland and improve urine flow.
• Prazosin is used to cause vasodilation and decrease blood pressure in patients with hypertension.

Alpha-2 antagonists: This classification is used in research, but has limited clinical application.

Beta Antagonists: There are two types of beta antagonists: selective beta blockers, which inhibit Beta-1 receptors and affect the heart only, and nonselective beta blockers, that block both Beta-1 and Beta-2 receptors, thus affecting both the heart and lungs. Beta-blockers are also referred to as having negative chronotropic (decreased heart rate), negative inotropic (decreased force of contraction), and negative dromotropic (decreased speed of conduction between SA and AV nodes) properties. It is also important for a nurse to remember that beta-blockers can mask the usual hypoglycemic symptoms of tremor, tachycardia, and nervousness in patients with diabetes.

Beta-1 antagonists: Beta-1 antagonists primarily block receptors in the heart, causing decreased heart rate and decreased blood pressure. An example is metoprolol, a selective beta-blocker used to treat high blood pressure, chest pain due to poor blood flow to the heart, and several conditions involving an abnormally fast heart rate.

Beta-2 antagonists: Nonselective beta-blockers block Beta-1 receptors and Beta-2 receptors in the lungs. An example is propranolol, which is used to lower blood pressure by decreasing the heart rate and cardiac output. However, it can also cause bronchoconstriction by inadvertently blocking Beta-2 receptors, so it must be used cautiously in patients with asthma or COPD.

Parasympathetic Nervous System

Acetylcholine (ACh) stimulates nicotinic and muscarinic receptors. Drugs that stimulate nicotinic and muscarinic receptors are called cholinergics. Medications are primarily designed to stimulate muscarinic receptors. Nicotine stimulates pre- and post-ganglionic nicotinic receptors, causing muscle relaxation and other CNS effects. An example of a medication designed to stimulate nicotinic receptors is the nicotine patch, used to assist with smoking cessation.

Muscarinic agonists are also called parasympathomimetics and primarily cause smooth muscle contraction, resulting in decreased heart rate, bronchoconstriction, increased gastrointestinal/genitourinary tone, and pupillary constriction. There are two types of muscarinic agonists: direct-acting and indirect-acting. Direct-acting agonists bind to the muscarinic receptor. Indirect-acting muscarinic agonists work by preventing the breakdown of ACh, thus increasing the amount of acetylcholine available to bind receptors.

Examples of direct-acting muscarinic agonist medications include:

• Pilocarpine: Used to treat glaucoma by causing the ciliary muscle to contract and allow for the drainage of aqueous humor
• Bethanechol: Used for urinary retention by stimulating the bladder causing urine output

Examples of indirect-acting muscarinic agonist medications include:

• Pyridostigmine: Used to reverse muscle weakness in patients with myasthenia gravis
• Physostigmine: Used to treat organophosphate insecticide poisoning
• Donepezil: Enhances memory in some patients with early Alzheimer’s disease

Muscarinic antagonists are referred to as anticholinergics or “parasympatholytics.” Anticholinergics inhibit ACh and allow the SNS to dominate, creating similar effects as adrenergics. Their overall use is to relax smooth muscle. “SLUDGE” is a mnemonic commonly used to recall the effects of anticholinergics: Salivation decreased, Lacrimation decreased, Urinary retention, Drowsiness/dizziness, GI upset, Eyes (blurred vision/dry eyes).  Anticholinergics may also cause confusion and constipation and must be used cautiously in the elderly. See Figure 4.2i for an illustration of the  "SLUDGE" effects of anticholinergics.

Examples of anticholinergic medications include:

• Atropine: Specific anticholinergic responses are dose-related. Small doses of atropine inhibit salivary and bronchial secretions and sweating; moderate doses dilate the pupil, inhibit accommodation, and increase the heart rate (vagolytic effect); larger doses will decrease motility of the gastrointestinal (GI) and urinary tracts; very large doses will inhibit gastric acid secretion
• Oxybutynin: Relaxes overactive bladder
• Benztropine: Reduces tremor and muscle rigidity in Parkinson’s disease or in treatment of extrapyramidal reactions from antipsychotic medications
• Scopolamine: Decreases GI motility and GI secretions; used for motion sickness and post-operative nausea and vomiting ,,,

Fig 4.2i “SLUDGE” Effects of Anticholinergics: Salivation decreased, Lacrimation decreased, Urinary retention, Drowsiness/Dizziness, GI upset, Eyes (blurred vision/dry eyes). Also may cause confusion and constipation

Image Descriptions

Figure 4.2b image description: Flow chart of the components of the Nervous System and ANS receptors.

Nervous System

1. Central
2. Peripheral
   1. Sensory
   2. Motor
      1. Somatic
      2. Autonomic (ANS)
         1. Sympathetic (SNS)
            1. Alpha 1
            2. Alpha 2
            3. Beta 1
            4. Beta 2
         2. Parasympathetic (PNS)
            1. Nicotinic
            2. Muscarinic [Return to Figure 4.2b]

Figure 4.2d image description: The automatic nervous system neurons signals via the preganglionic neurons to postganglionic neurons to the target organs.

1. Parasympathetic Nervous System
   1. Preganglionic neuron: soma is usually in the brain-stem or sacral (toward the bottom) spinal cord
   2. Neurotransmitter released from the preganglionic synapse: acetylcholine
   3. Postganglionic neutron: soma is usually in a ganglion near the target organ
   1. Neurotransmitters released from postganglionic synapse: acetylcholine or nitric oxide
   2. Target organ
   3. “Rest and digest” response is activated
2. Sympathetic Nervous System
   1. Preganglionic neutron: soma is usually in the spine
   2. Neurotransmitter from the preganglionic synapse: acetylcholine
   3. Postganglionic neutron: soma is in a sympathetic ganglion, located next to the spinal chord
   4. Neurotransmitters released from postganglionic synapse: norepinephrine
   5. Target organ
   6. “Fight or flight” response is activated [Return to Figure 4.2d]

Figure 4.2h image description: Effects of Medications Stimulating Beta 2 Receptors in the Lungs

1. 1. The bronchiole is normal. The muscle is relaxed, open, and smooth.
   2. The bronchiole is constricted. The muscle is tightened, which constricts the airways. Excessive mucus may occur.
   3. Medication dilates the constricted bronchiole. The bronchiole is normal again. The muscle is open and relaxed once more and the excess mucus can be cleared. [Return to Figure 4.2h]

The next sections will focus on medications related to regulating the autonomic nervous system.  Before we do that, it is important to re-examine the nursing process in guiding the nurse who administers ANS medications.  The nursing process consists of assessment, diagnosis, outcome identification, planning, implementation of interventions, and evaluation.  Because diagnosis, outcome identification, and planning are specifically tailored to the individual client, we will broadly discuss considerations related to assessment, implementation of interventions, and evaluation when administering antimicrobials.

Assessment

Recognizing cues…

Recall that assessment is all about recognizing and analyzing “cues” from your conversations and physical assessment of your clients.

Many types of medications stimulate or inhibit specific ANS receptors. By knowing the effects, it becomes easy for the nurse to recognize side effects resulting from the stimulation or inhibition of ANS neuroreceptors. Medications that stimulate ANS receptors often impact the heart, lungs, and blood vessels, so the nurse must often monitor blood pressure, heart rate, and lung sounds carefully for expected therapeutic effects and side effects. Anticholinergics cause muscle relaxation and can cause urinary retention, constipation, and dry mouth. The nurse should anticipate and assess for these side effects, and manage them as needed for client comfort.

Planning

Next, plan (refine your hypothesis), and take action.

When planning your care, remember to prioritize and refine your hypotheses based on your client assessment.

Common goals include:

• Client will understand the effects of their medication, and the importance of adhering to the medication regimen.
• Client’s vital signs will be within the desired range.

Implementation of Interventions

A nurse should be aware of parameters to administer or withhold medications affecting the autonomic nervous system. If the order parameters are unclear, the nurse should withhold the medication following safe administration guidelines, and notify the prescriber.  For example, when no parameters are provided, blood pressure medications should not be administered if the client’s apical heart rate is less than 60  beats per minute and/or the systolic blood pressure is less than 100 mmHg.

Report any marked vital signs, changes or suspected adverse effects.

Implement fall precautions, when needed, based on anticipated side effects of ANS medications.

Evaluation

Finally, evaluate the outcomes of your action.

It is always important for nurses to know the reason why a medication is ordered for a specific client, so evaluation of therapeutic effectiveness can be documented. For example, if the purpose of medication is to improve urine flow, then improvement should be seen and documented. Otherwise, the side effects may not warrant the use of the medication.

Classes of medication, categorized according to neuroreceptor, are further discussed in more detail below. Figure 4.5a summarizes how ANS drugs are classified.

Figure 4.5a Classification of drugs acting on the ANS [Figure 4.5a Image Description]

Table 4.5 further contrasts agonist and antagonist medications for each ANS neuroreceptor.

Supplementary Videos:  See the supplementary videos below related to sympathetic and parasympathetic nervous system medications.

Image Descriptions

Figure 4.5a Classification of drugs acting on the ANS Image Description

Drugs acting on the ANS are classified by the receptor type affected:

• Adrenergic drugs
  • α1, α2
  • β1, β2
• Cholinergic drugs
  • nicotinic (N1, N2)
  • muscarinic (M1, M2, M3)

Drugs acting on the ANS are classified by the effect on the receptor:

1. agonist
2. antagonist

[Return to Figure 4.5a]

Mechanism of Action: Nicotine binds to and activates nicotinic acetylcholine receptors, mimicking the effect of acetylcholine at these receptors.

Indications for Use: Nicotine patches are used as an aid to smoking cessation and for the relief of nicotine withdrawal signs and symptoms as part of a comprehensive behavioral smoking cessation program.

Nursing Considerations Across the Lifespan: Nicotine is not recommended for children or pregnant women. Based on available data, pregnancy outcomes are similar following maternal nicotine replacement therapy (NRT) when compared to cigarette smoking.

Nicotine is a hazardous drug; use safe handling and disposal precautions. Apply one new patch every 24 hours on skin that is dry, clean, and hairless. Remove backing from patch and immediately press onto skin. Hold for 10 seconds. Wash hands after applying or removing the patch. Dispose of the used patches by folding sticky ends together and putting in pouch. The used patch should be removed and a new one applied to a different skin site at the same time each day. Do not apply more than one patch at a time.  Discontinue use and call provider if an allergic reaction occurs, such as difficulty breathing or rash, or symptoms of nicotine overdose occur, such as nausea, vomiting, dizziness, weakness, and rapid heartbeat.  It may also cause vivid dreams or sleep disturbances.  If these occurrences occur, clients should be counselled to remove the patch at bedtime and apply a new one in the morning.

Patient Teaching & Education: Emphasize that the client should stop smoking completely while on nicotine replacement therapy to avoid additive nicotine levels higher than smoking alone. Advise clients that participating in a comprehensive smoking cessation program improves success.  If using a nicotine patch, client should be aware that skin sensitivity at the site of patch placement typically resolves within one hour.

Alert: Advise client to keep all nicotine products, including used inhaler cartridges, nasal spray bottles, and patches out of the reach of children and pets.

Nicotine Patch Medication Card

Now let’s take a closer look at the medication card on nicotine patch. Medication cards assist students to learn key points about each medication class.  Basic information related to a common generic medication in this class is outlined, including administration considerations, therapeutic effects, and side effects/adverse effects. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Pilocarpine is a muscarinic receptor agonist.

Mechanism of Action: Pilocarpine causes the ciliary muscle to contract, allowing for the drainage of aqueous humor from the anterior chamber of the eye and reducing intraocular pressure related to glaucoma.

Indications for Use: Pilocarpine is used to treat glaucoma.

Nursing Considerations Across the Lifespan: Muscarinic receptor agonists, such as pilocarpine, can be used in children and older adults. There are no necessary dose adjustments for kidney or liver dysfunction in older adults.

Remove contact lens before administration. Apply light finger pressure on lacrimal sac for 2 minutes after instilling to minimize systemic absorption.

Patient Teaching & Education:  Advise the client to use caution with night driving.  Additionally, use of this medication can cause hypotension.

Pilocarpine Medication Card

Now let’s take a closer look at the medication card on pilocarpine. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Medication Card 4.7.1: Pilocarpine

Class: Muscarinic Agonist

Prototypes: pilocarpine

Therapeutic Effects

• Controls intraocular pressure in glaucoma

Administration

• Remove contact lens before administration
• Apply light finger pressure on lacrimal sac for 2 minutes after instilling to minimize systemic absorption

Indications

• Management of intraocular pressure in glaucoma

Side Effects

• Caution client with night driving as medication can decrease visual acuity

Nursing Considerations

• Apply pressure on lacrimal sac after instilling

Figure 4.7a

Media Attributions

• Figure 4.7a: Lacrimal Sac by OpenStax Microbiology is licensed under a CC BY 2.0 licence.

Atropine is a muscarinic antagonist.

Mechanism of Action: Specific anticholinergic responses are dose-related. Small doses of atropine inhibit salivary and bronchial secretions and sweating. Moderate doses dilate the pupil, inhibit accommodation, and increase the heart rate (vagolytic effect). Large doses decrease motility of the gastrointestinal and urinary tracts, and very large doses will inhibit gastric acid secretion.

Indications for Use: Varying dosages are used preoperatively to diminish secretions, to stimulate the heart rate in conditions causing bradycardia, or to treat muscarinic symptoms of insecticide (organophosphorus or carbamate) poisoning or mushroom poisoning.

Nursing Considerations Across the Lifespan: As with all anticholinergics, use with caution with the elderly, because elderly clients may react with agitation or drowsiness. Heat stroke may occur in the presence of high temperatures. Immediately report symptoms of overdose: urine retention, abnormal heartbeat, dizziness, passing out, difficulty breathing, weakness, or tremors. Physostigmine has been used to reverse anticholinergic effects.

Atropine can be given to pediatric clients, with doses adjusted according to the child weight.

Patient Teaching & Education: Advise clients that use of these medications may cause dizziness and drowsiness, so clients should be aware of potential impact on their level of alertness.  Additionally, use of medications may cause dry mouth, and frequent oral hygiene is encouraged.  The use of atropine may cause urinary retention in males with benign prostatic hypertrophy (BPH).

Atropine Medication Card

Now let’s take a closer look at the medication card on atropine in Table 4.8. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Pseudoephedrine and phenylephrine are Alpha-1 agonists.

Mechanism of Action: Alpha-1 agonists stimulate alpha receptors in the respiratory tract, causing constriction of blood vessels and shrinkage of swollen nasal mucous membranes, thus increasing airway patency and reducing nasal congestion.

Indications for Use: These drugs are commonly used for symptomatic relief in upper respiratory infections.

Nursing Considerations Across the Lifespan:

There is limited data on whether pseudoephedrine can be used in children under the age of 4 years old, so it should be avoided. It is safe to use in older adult populations, and no dosage adjustments are required for renal or liver dysfunction.

Pseudoephedrine has had recent limitations placed on its use because it is a common ingredient in the illicit manufacturing of the drug methamphetamine. Pharmacies now require individuals to provide identification to purchase pseudoephedrine and must track the number of purchases. As a result, most over-the-counter decongestants now contain phenylephrine. Both should be used cautiously in clients with glaucoma, hypertension, or an enlarged prostate gland and are contraindicated in clients taking monoamine oxidase inhibitors (MAOIs), an older class of medication used to treat depression. Monitor for elevated blood pressure, urinary retention, nervousness, or difficulty sleeping. Do not administer within 2 hours of bedtime.

Patient Teaching & Education:  Clients should be instructed to take medication as prescribed and be careful not to double-dose.  If they experience nervousness, breathing difficulties, or heart rate changes, they should notify their healthcare provider.

Phenylephrine and Pseudoephedrine Medication Card

Now let’s take a closer look at the medication grid on phenylephrine and pseudoephedrine in Table 4.9. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Tamsulosin is an Alpha-1 antagonist.

Mechanism of Action:  Tamsulosin selectively blocks alpha receptors in the prostate, leading to the relaxation of smooth muscles in the bladder, neck, and prostate, thus improving urine flow and reducing symptoms of benign prostatic hypertrophy (BPH).

Indications for Use: Tamsulosin is used to treat BPH.

Nursing Considerations Across the Lifespan: Alpha-1 antagonists are not recommended for children under the age of 2 years old.  They are safe to use in older adults, but dose adjustments need to be made based on kidney function.  There is limited information about whether alpha-1 antagonists, such as tamsulosin, can be used in pregnancy.

Avoid using with other alpha-blockers. Tamsulosin is contraindicated with strong CYP3A4 inhibitors such as ketoconazole. Assess and monitor blood pressure, especially after first dose because tamsulosin may cause orthostatic hypotension.

Patient Teaching & Education: Advise clients to change positions slowly because the drug may cause orthostatic blood pressure changes.  Additionally, the client should take the medication at the same time each day.  The client should follow up with their healthcare provider to assess the effectiveness of the medication.

Tamsulosin Medication Card

Now let’s take a closer look at the medication grid on tamsulosin. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Clonidine is an Alpha-2 antagonist.

Mechanism of Action:  Clonidine reduces sympathetic outflow from the central nervous system and decreases peripheral resistance and renal vascular resistance.

Indications for Use: Clonidine is used to treat hypertension (HTN) and attention deficit hyperactivity disorder (ADHD).

Nursing Considerations Across the Lifespan: Alpha-2 antagonists can be used safely in pediatric and older adult populations.  For pediatrics, dose adjustments need to be made based on the child’s weight, and titrated slowly.  In older adult populations, dose adjustments are necessary when there is underlying kidney dysfunction.

Nurses need to monitor blood pressure and pulse rate frequently when giving these medications. Dosage is usually adjusted to the client’s blood pressure and can cause hypotension, bradycardia, and sedation. Rebound hypertension may occur if stopped abruptly.

Patient Teaching & Education: Clients should be taught the importance of adhering to the same dosing schedule each day.  Clients may experience orthostatic blood pressure changes and should be cautioned against the use of alcohol while taking this medication.  Additionally, clients may experience increased susceptibility to blood pressure changes when exercising and exposed to hot environments.  If the client experiences mental depression as a side effect of the medication, a different medication therapy may be needed.

Clonidine Medication Card

Now let’s take a closer look at the medication grid on clonidine. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Alpha-2 Antagonists

A2 antagonists are used in research with limited clinical application.

Dobutamine is a Beta-1 agonist.

Mechanism of Action:  Dobutamine stimulates Beta-1 receptors to increase heart rate, force of contraction, and conduction velocity.

Indications for Use: Dobutamine is used to treat cardiogenic shock and severe heart failure to increase contractility and cardiac output.

Nursing Considerations Across the Lifespan: Beta-1 agonists can safely be administered to pediatric clients, but doses must be adjusted according to weight. These medications are also safe in the older adult population, with no special dose adjustments for renal or liver insufficiency. Beta-1 agonists should not be given in pregnancy, if they can be avoided.

In IV administration, dilute concentration before administering. Continuously monitor electrocardiogram (ECG), blood pressure, cardiac output, and urine output during therapy. This drug can cause a marked increase in heart rate and blood pressure. Report all adverse reactions promptly, especially laboured breathing, angina, palpitations, and dizziness.

Patient Teaching & Education: The client should be instructed to inform the nurse immediately if they notice chest pain, shortness of breath, or numbness or tingling in the extremities.

Dobutamine Medication Card

Now let’s take a closer look at the  medication card for dobutamine. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Metoprolol is a selective Beta-1 antagonist.

Mechanism of Action: Metoprolol primarily blocks Beta-1 receptors in the heart, causing decreased heart rate and decreased blood pressure. However, higher doses can also block Beta-2 receptors in the lungs, causing bronchoconstriction.

Indications for Use:  Metoprolol is commonly used to treat high blood pressure, chest pain due to poor blood flow to the heart, as an early intervention during a myocardial infarction (MI), and in several heart conditions involving an abnormally fast heart rate.

Nursing Considerations Across the Lifespan: Beta-1 antagonists can be given to pediatric and older adult clients, but doses should be individualized based on client response.

Do not crush extended-release (ER) formulations. Always check client’s apical pulse rate before giving drug. Withhold the drug and call the prescriber immediately if the heart rate is slower than 60 beats/minute, unless other parameters are provided. In diabetic clients, monitor glucose level closely because the drug masks common signs and symptoms of hypoglycemia. The most serious potential adverse effects are shortness of breath, bradycardia, and worsening heart failure. Other adverse effects include fatigue, dizziness, depression, insomnia, nightmares, gastrointestinal upset, erectile dysfunction, dyspnea, and wheezing.

Safety Warning: When stopping therapy, the dosage should be tapered over 1 to 2 weeks because abrupt discontinuation may cause chest pain or myocardial infarction (MI).

Patient Teaching & Education: Patients should be instructed to take the medication as prescribed.  They should be advised that abrupt cessation of medication therapy may result in life-threatening cardiac arrhythmias.  Patients should also be taught how to self-check pulse and blood pressure to assess the effectiveness of medication therapy.  Additionally, they should be cautioned against sudden changes in position due to orthostatic blood pressure changes.  Patients may experience increased sensitivity to cold and should be cautioned to avoid caffeinated substances.

Metoprolol Medication Card

Now let’s take a closer look at the medication card for metoprolol. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Albuterol is a Beta-2 agonist.

Mechanism of Action: Albuterol is a selective Beta-2 agonist primarily used to cause bronchodilation in the lungs. However, Beta-2 receptors in the heart can also be stimulated, causing cardiovascular side effects.

Indications for Use:  Albuterol is commonly used to treat asthma and chronic obstructive pulmonary disease (COPD).

Nursing Considerations Across the Lifespan:

Monitor respiratory rate, oxygen saturation, and lungs sounds before and after administration. If more than one inhalation is ordered, wait at least 2 minutes between inhalations. Use a spacer device to improve drug delivery, if appropriate.

Beta-2 agonists are safe for administration in pediatric and older adult populations.

Adverse Effects: Albuterol can cause hypersensitivity or paradoxical bronchospasm.  It can also produce a clinically significant cardiovascular effect in some clients by causing increased heart rate and blood pressure, which may require the drug to be discontinued.

Patient Teaching & Education: Clients should remain consistent with the medication dosing regimen.  Individuals should contact their healthcare provider if they experience ongoing shortness of breath unrelieved with medication therapy.  If using an inhaler, the client should be sure to prime the inhaler prior to administering the dose of medication.  The medication can cause an unusual taste in the mouth, so clients should rinse their mouth with water after each use.

Albuterol Medication Card

Now let’s take a closer look at the medication card on albuterol. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Propranolol is a Beta-2 antagonist.

Mechanism of Action: Propranolol is a nonselective beta-blocker because of its inhibition of both Beta-1 and Beta-2 receptors.

Indications for Use: Propranolol is used to treat high blood pressure, angina, various heart dysrhythmias (to lower the heart rate), and essential tremors. It is also used after a myocardial infarction to reduce mortality by decreasing heart workload, and in migraine prevention.

Nursing Considerations Across the Lifespan: Nonselective beta blockers must be used cautiously with clients who have co-existing asthma or chronic obstructive pulmonary disease (COPD) because of the effects on Beta-2 receptors that could potentially cause bronchoconstriction. It can also mask symptoms of hypoglycemia in diabetics. Use with caution in clients with impaired hepatic or renal function. Give immediate-release (IR) formulations on an empty stomach. Do not crush extended-release (ER) formulations. Propranolol ER is not considered a simple milligram-for-milligram substitute for conventional propranolol. Check blood pressure and apical pulse before giving drug; withhold and notify prescriber if apical pulse is less than 60 beats per minute or systolic blood pressure is less than 100 mm Hg, unless other parameters are provided. During IV administration, monitor blood pressure, ECG, and heart rate frequently. The most serious adverse effects include bronchoconstriction, hypotension, bradycardia, and signs of worsening heart failure. Other adverse effects are similar to selective beta blockers like metoprolol.

Propranolol is safe to give to pediatric clients, with dose adjustments made according to response to medication.  No dose adjustments are needed for renal or liver dysfunction.

Safety Warning: Abrupt withdrawal of this drug may cause exacerbation of angina or a myocardial infarction. To discontinue this drug, gradually reduce dosage over 1 to 2 weeks.

Patient Teaching & Education: Clients should be instructed to follow the medication dosing regimen.  Stopping medication therapy abruptly may cause life-threatening arrhythmias.  Clients should be instructed on how to self-assess pulse and blood pressure to evaluate medication effectiveness.  The medication may cause increased susceptibility to orthostatic blood pressure changes and increased sensitivity to cold.

Propranolol Medication Card

Now let’s take a closer look at the medication Card for propranolol. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Catecholamines

Epinephrine and norepinephrine (NE) are adrenergics that stimulate the beta and alpha receptors on the target cell. Dopamine has dose-dependent effects on targeted arteries in the kidneys, heart, and brain.

Epinephrine (Alpha and Beta Receptor Agonist):  Epinephrine acts on both alpha- and beta-adrenergic receptors and is used in several routes including intravenously (IV), subcutaneously, intramuscularly, and via inhalation. Epinephrine decreases vasodilation and increases vascular permeability through its alpha-adrenergic receptor action, which can lead to loss of intravascular fluid volume and hypotension. Through its action on beta-adrenergic receptors, epinephrine causes bronchial smooth muscle relaxation and helps alleviate bronchospasm, wheezing, and dyspnea that may occur during anaphylaxis.

Indications for Use: Epinephrine is used for severe allergic reactions (anaphylaxis), acute bronchospasm during asthma attacks, cardiac resuscitation, hypotension in severe shock, or for local injection to control superficial bleeding.

Nursing Considerations Across the Lifespan: Epinephrine is contraindicated for use in fingers, toes, ears, nose, or genitalia when used with local anaesthetic due to the vasoconstrictive action. Contraindicated in clients with narrow-angle glaucoma. Administer with caution to the elderly and those with pre-existing cardiovascular disease. When administering IV, monitor vitals (blood pressure, heart rate and respiratory rate) and cardiovascular and respiratory systems closely; if blood pressure increases sharply, give rapid-acting vasodilators. Monitor IV site for extravasation. Discard IV solution if discoloured.

Epinephrine can be used across the lifespan. It can also be given to pregnant women in the case of anaphylaxis.

Patient Teaching & Education with EpiPen:  Epinephrine formulated in a pen for injection is known as EpiPen.  EpiPen is used for severe allergic reactions after exposure to an allergen like a bee sting. Check expiration date, store at room temperature, and protect from light. Effects fade after 15-20 minutes, so seek medical care immediately.

Norepinephrine is another catecholamine, and is used as a peripheral vasoconstrictor (due to alpha-adrenergic action) and as an inotropic stimulator of the heart and dilator of coronary arteries (due to beta-adrenergic action) in clients with critically low blood pressure.

Epinephrine and Norepinephrine Medication Card

Now let’s take a closer look at the medication card for epinephrine and norepinephrine. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Dopamine is another type of catecholamine specifically used to improve perfusion of organs, improve cardiac output, and increase blood pressure.

Mechanism of Action: In low doses, dopamine mainly stimulates dopamine receptors and dilates the renal vasculature. Moderate doses of dopamine stimulate beta receptors for a positive inotropic effect. Higher doses also stimulate alpha receptors, constricting blood vessels and increasing blood pressure.

Indications for Use:  Dopamine is used to treat shock, improve perfusion to vital organs, increase cardiac output, and correct hypotension.

Nursing Considerations Across the Lifespan: During infusion, frequently monitor blood pressure, cardiac output, urine output, and colour and temperature of limbs. If urine flow decreases without hypotension, notify prescriber because dosage may need to be reduced. Concurrent alpha or beta-blockers can antagonize dopamine. Adverse effects include hypotension, tachycardia, palpitations, and decreased blood flow to the extremities.

Dopamine is safe to adminster to pediatric and older adults.

Patient Teaching & Education: Clients should contact their health care provider immediately if experiencing unusual sweating, dizziness, heart palpitations, or chest pain.

Dopamine Medication Card

Now let’s take a closer look at the medication card for dopamine. Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Acetylcholine (ACh): Binds to both nicotinic receptors and muscarinic receptors in the PNS.

Adrenergic: Postganglionic neuron where neurotransmitters norepinephrine and epinephrine are released. Includes alpha (α) receptors and beta (β) receptors.

Adrenergic Agonist: Mimics the effects of the body’s natural SNS stimulation on alpha (α) and beta (β) receptors. Also called sympathomimetics.

Adrenergic Antagonist: Blocks the effects of the SNS receptors.

Anticholinergics: Inhibit acetylcholine (ACh), which allows the SNS to dominate. Also called parasympatholytics or muscarinic antagonists. Overall use is to relax smooth muscle.

Autonomic Nervous System: Controls cardiac and smooth muscle, as well as glandular tissue; associated with involuntary responses.

Catecholamines: Include norepinephrine, epinephrine, and dopamine. Stimulate the adrenergic receptors.

Central Nervous System (CNS): Anatomical division of the nervous system located within the cranial and vertebral cavities, namely the brain and spinal cord.

Cholinergic: Postganglionic neuron where acetylcholine (ACh) is released that stimulates nicotinic receptors and muscarinic receptors. Also relating to drugs that inhibit, enhance, or mimic the action of ACh.

Chronotropic: Drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the nerves that influence it, such as by changing the rhythm (increasing) produced by the sinoatrial node. Positive chronotropes increase heart rate; negative chronotropes decrease heart rate.

Dromotropic: Stimulation causes increased speed of conduction between SA and AV node.

Fight-or-Flight Response: The response when the SNS is stimulated, causing the main effects of increased heart rate, increased blood pressure, and bronchodilation.

Glyconeogenesis: The breakdown of glycogen into glucose, causing elevated blood glucose.

Homeostasis (in ANS): Balance between the SNS and PNS. At each target organ, dual innervation determines activity. For example, SNS stimulation causes the heart rate to increase, whereas PNS stimulation causes the heart rate to decrease.

Hyperglycemia: Elevated blood glucose.

Inotropic: Stimulation causes increased force of contraction.

Involuntary Responses: Responses that the brain controls without the need for conscious thought.

Motor Neurons: Consist of the somatic nervous system that stimulates voluntary movement of muscles and the autonomic nervous system that controls involuntary responses.

Muscarinic Agonists: Also called parasympathomimetics. Primarily cause smooth muscle contraction, resulting in decreased HR, bronchoconstriction, increased gastrointestinal/genitourinary tone, and pupil constriction.

Neurons: Cells that carry electrical impulses to the synapse of a target organ.

Nonselective Beta Blockers: Medications that block both Beta-1 and Beta-2 receptors, thus affecting both the heart and lungs.

Parasympathetic Division (PNS): Includes nerves outside the brain and spinal cord. Associated with the “rest and digest” response. Stimulation of PNS causes decreased heart rate, decreased blood pressure via vasodilation, bronchial constriction, and stimulates intestinal motility, salivation, and relaxation of the bladder.

Parasympatholytics: Inhibit acetylcholine (ACh), which allows the SNS to dominate. Also called anticholinergics or muscarinic antagonists.

Parasympathomimetics: Also called muscarinic agonists. Primarily cause smooth muscle contraction, resulting in decreased HR, bronchoconstriction, increased GI/GU tone, and pupil constriction.

Peripheral Nervous System (PNS): An anatomical division of the nervous system that is largely outside the cranial and vertebral cavities, namely all parts except the brain and spinal cord.

Postganglionic Neurons: Differ for the SNS and PNS branches. Postganglionic neurons of the autonomic system are classified as either cholinergic, meaning that acetylcholine (ACh) is released, or adrenergic, meaning that norepinephrine is released.

Preganglionic Neurons: All preganglionic neurons (in the SNS and PNS) release acetylcholine (ACh).

Selective Beta Blocker: Medications that mostly inhibit B1 receptors.

Sensory Neurons: Sense the environment and conduct signals to the brain that become a conscious perception of that stimulus.

“SLUDGE”: Mnemonic for the effects of anticholinergics: Salivation decreased, Lacrimation decreased, Urinary retention, Drowsiness/dizziness, GI upset, Eyes (blurred vision/dry eyes).

Somatic Nervous System: Causes contraction of skeletal muscles; associated with voluntary responses.

Sympathetic Division (SNS): Associated with the “fight-or-flight response.” Stimulation causes the main effects of increased heart rate, increased blood pressure via the constriction of blood vessels, and bronchodilation.

Sympathomimetics: Mimic the effects of the body’s natural SNS stimulation of adrenergic receptors. Also called adrenergic agonists.

Synapse: The connection between the neuron and its target cell.

Gas Exchange Introduction

Every year millions of Canadians visit their health care provider for respiratory diseases such as allergies, asthma, bronchitis, common cold, chronic obstructive pulmonary disease (COPD), and pneumonia.

Respiratory diseases are a major public health concern in Canada.  The cost of chronic respiratory diseases has a great impact on health care costs in Canada.  Currently, 3 million people in Canada, about 9.5% of Canada’s population, have asthma. Interestingly, 2 million adults have been diagnosed with COPD, and approximately 1.5 million people have not yet been diagnosed. The burden of respiratory diseases affects individuals and their families, schools, workplaces, neighborhoods, and cities.  Improving health surveillance efforts will help to support and design new policies and programs that will positively impact the effects of these diseases on Canadians. The Canadian Chronic Disease Surveillance System (CCDSS) researches and identifies data on chronic diseases such as asthma and COPD to seek further solutions for the improvement of health for diagnosed Canadians.

As you transition through this chapter and begin the section on medications to treat, you will notice that multiple medication classifications are discussed but there is only one medication card to be completed per chapter. These medication cards were developed as a guide for you to use in your own practice to build you own medication cards. There is a section that provides these tools in a word format for you to download and edit as needed. But before we look at the medications, let’s review the anatomy and physiology.

Concepts Related to Respiratory Medications

Overview of the Respiratory System

The purpose of the respiratory system is to perform gas exchange. Pulmonary ventilation provides air to the alveoli for this gas exchange process. At the respiratory membrane where the alveolar and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting. It is through this mechanism that blood is oxygenated and carbon dioxide, the waste product of cellular respiration, is removed from the body. See Figure 5.2a

Figure 5.2a Example of Gas Exchange Concept Map [Image Description]

The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as during childbirth or coughing.

See Figure 5.2b illustrating major respiratory structures

Figure 5.2b  Major Respiratory Structures: The major respiratory structures span the nasal cavity to the diaphragm

Functionally, the respiratory system can be divided into a conducting zone and a respiratory zone. The conducting zone of the respiratory system includes the organs and structures not directly involved in gas exchange. The gas exchange occurs in the respiratory zone.

Conducting Zone

The major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air. Several structures within the conducting zone perform other functions as well. The epithelium of the nasal passages, for example, is essential to sensing odors, and the bronchial epithelium that lines the lungs can metabolize some airborne carcinogens.

The cilia of the respiratory epithelium help remove the mucus and debris from the nasal cavity with a constant beating motion, thus sweeping materials toward the throat to be swallowed. Interestingly, cold air slows the movement of the cilia, resulting in the accumulation of mucus that may, in turn, lead to a runny nose during cold weather. This moist epithelium functions to warm and humidify incoming air. Capillaries located just beneath the nasal epithelium warm the air by convection.

Bronchial Tree

The trachea branches into the right and left primary bronchi at the carina. A bronchial tree (or respiratory tree) is the collective term used for these multiple-branched bronchi. The main function of the bronchi, like other conducting zone structures, is to provide a passageway for air to move into and out of each lung. In addition, the mucous membrane traps debris and pathogens.

A bronchiole branches from the tertiary bronchi. Bronchioles, which are about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1,000 terminal bronchioles in each lung. The muscular walls of the bronchioles do not contain cartilage like those of the bronchi. This muscular wall can change the size of the tubing to increase or decrease airflow through the tube.

Respiratory Zone

In contrast to the conducting zone, the respiratory zone includes structures that are directly involved in gas exchange. See Figure 5.2c for an illustration of the respiratory zone. The respiratory zone begins where the terminal bronchioles join a respiratory bronchiole, the smallest type of bronchiole, which then leads to an alveolar duct, opening into a cluster of alveoli.

Figure 5.2c The Respiratory Zone. Bronchioles lead to alveolar sacs in the respiratory zone where gas exchange occurs

Alveoli

An alveolar duct is a tube composed of smooth muscle and connective tissue, which opens into a cluster of alveoli. An alveolus is one of the many small, grape-like sacs that are attached to the alveolar ducts.

An alveolar sac is a cluster of many individual alveoli that are responsible for gas exchange. See Figure 5.2d for an illustration of the structures of the respiratory zone.

Figure 5.2d Structures of the Respiratory Zone. The alveolus is responsible for gas exchange

Respiratory Rate and Control of Ventilation

Breathing usually occurs without thought, although at times you can consciously control it, such as when you swim under water, sing a song, or blow bubbles. The respiratory rate is the total number of breaths, or respiratory cycles, that occur each minute. Respiratory rate can be an important indicator of disease, as the rate may increase or decrease during an illness. The respiratory rate is controlled by the respiratory center located within the medulla oblongata in the brain, which responds primarily to changes in carbon dioxide, oxygen, and pH levels in the blood.

The normal respiratory rate of a child decreases from birth to adolescence. A child under 1 year of age has a normal respiratory rate between 30 and 60 breaths per minute, but by the time a child is about 10 years old, the normal rate is closer to 18 to 30. By adolescence, the normal respiratory rate is similar to that of adults, 12 to 18 breaths per minute.

Neurons that stimulate the muscles of the respiratory system are responsible for controlling and regulating pulmonary ventilation. The major brain centers involved in pulmonary ventilation are the medulla oblongata and the pontine respiratory group. (See Figure 5.2e for an illustration of the respiratory centers of the brain.)

Figure 5.2e Respiratory Centers of the Brain

Supplementary Videos:  See the supplementary videos below related to respiratory anatomy and physiology.

Image Description

Figure 5.2a Example of Gas Exchange Concept Map image description: This concept map illustrates the steps of gas exchange. The flow is as follows:

• Respirations
  • Inhalation of air
• Expiration to atmosphere
• Alveoli
  • Pulmonary capillaries
  • Diffusion
  • Hemoglobin carrying capacity
    • Perfusion
    • Delivery of oxygen and nutrients
  • Cells lining alveoli
• Cellular uptake of oxygen and nutrients
• Cellular metabolism and energy
  • Waste products – carbon dioxide
  • Capillaries carrying waste out of cell through perfusion
    • Expiration [Return to image]

Allergies

Allergies occur when your immune system reacts to a foreign substance – such as pollen, bee venom, pet dander, or food – that doesn’t cause a reaction in most people.

Your immune system produces substances known as antibodies. When you have allergies, your immune system makes antibodies that identify a particular allergen as harmful, even though it isn’t. When you come into contact with the allergen, your immune system’s reaction can inflame your skin, sinuses, airways, or digestive system.

The severity of allergies varies from person to person and can range from minor irritation to a potentially life-threatening emergency. While most allergies can’t be cured, treatments can help relieve allergy symptoms.

Allergy symptoms, which depend on the substance involved, can affect airways, sinuses, and nasal passages, skin, and the digestive system.

Hay fever, also called allergic rhinitis, can cause:

• Sneezing
• Itching of the nose, eyes, or roof of the mouth
• Runny, stuffy nose
• Watery, red or swollen eyes (conjunctivitis)

A food allergy can cause:

• Tingling in the mouth
• Swelling of the lips, tongue, face, or throat
• Hives
• Anaphylaxis

An insect sting allergy can cause:

• Large area of swelling (edema) at the sting site
• Itching or hives all over the body
• Cough, chest tightness, wheezing, or shortness of breath
• Anaphylaxis

A drug allergy can cause:

• Hives
• Itchy skin
• Rash
• Facial swelling
• Wheezing
• Anaphylaxis

Atopic dermatitis, an allergic skin condition also called eczema, can cause skin to:

• Itch
• Redden
• Flake or peel

Anaphylaxis

Some types of allergies, including allergies to foods and insect stings, can trigger a severe reaction known as anaphylaxis. As a life-threatening medical emergency, anaphylaxis can cause a client to go into shock. Signs and symptoms of anaphylaxis include:

• Loss of consciousness
• Drop in blood pressure
• Severe shortness of breath
• Skin rash
• Lightheadedness
• Rapid, weak pulse
• Nausea and vomiting

Asthma

Asthma is a chronic disease affecting the lungs of both children and adults,  characterized by inflammation, edema, and bronchospasm of the airways, which inhibits air from entering the lungs. In addition, excessive mucus secretion can occur, which further contributes to airway blockage. Cells of the immune system, such as eosinophils and mononuclear cells, may also be involved in infiltrating the walls of the bronchi and bronchioles.

Bronchospasms occur periodically and lead to an “asthma attack.” An attack may be triggered by environmental factors such as dust, pollen, pet hair, or dander; changes in the weather; mold; tobacco smoke; respiratory infections; exercise; and stress.

See Figure 5.3 for an illustration of how asthma affects the airways.

Figure 5.3a How Asthma Affects the Airways [Figure 5.3a Image Description]

Symptoms of an asthma attack involve coughing, shortness of breath, wheezing, and tightness of the chest. Symptoms of a severe asthma attack that requiring immediate medical attention include difficulty breathing that results in cyanotic lips or face, confusion, drowsiness, a rapid pulse, sweating, and severe anxiety.

The severity of the condition, frequency of attacks, and identified triggers influence the type of medication that an individual may require. Long-term treatments are used for clients with severe asthma. Short-term, fast-acting drugs are used to treat an asthma attack and are typically administered via an inhaler or nebulizer.  View the following video for additional insight into how asthma works.

Bronchitis

Bronchitis is an inflammation of the lining of the bronchial tubes, which carry air to and from the lungs. People who have bronchitis often cough up thickened mucus, which can be discolored. Bronchitis may be either acute or chronic.

Often developing from a cold or other respiratory infection, acute bronchitis is very common. Acute bronchitis, also called a chest cold, usually improves within a week to 10 days without lasting effects, although the cough may linger for weeks.

Chronic bronchitis, a more serious condition, is a constant irritation or inflammation of the lining of the bronchial tubes, often due to smoking. Chronic bronchitis is one of the conditions included in COPD.

Symptoms for either acute bronchitis or chronic bronchitis may include:

• Cough
• Production of mucus (sputum), which can be clear, white, yellowish-gray, or green in color — rarely, it may be streaked with blood
• Fatigue
• Shortness of breath
• Slight fever and chills
• Chest discomfort

Cold

The common cold is a viral infection of the upper respiratory tract. Many types of viruses can cause a common cold.  Children younger than 6 are at greatest risk of colds, but healthy adults can also expect to have two or three colds annually.  Most people recover from a common cold in a week or 10 days. Symptoms might last longer in people who smoke.

Symptoms of a common cold usually appear one to three days after exposure to a cold-causing virus. Signs and symptoms, which can vary from person to person, might include:

• Runny or stuffy nose
• Sore throat
• Cough
• Congestion
• Slight body aches or a mild headache
• Sneezing
• Low-grade fever
• Generally feeling unwell (malaise)

Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory lung disease that causes obstructed airflow out of the lungs. Symptoms include breathing difficulty, cough, mucus (sputum) production, and wheezing. It is often caused by long-term exposure to irritating gases or dust, and most often occurs due to smoking. People with COPD are at increased risk of developing heart disease, lung cancer, and a variety of other conditions.

Emphysema and chronic bronchitis are the two types of COPD. Emphysema is a condition in which the alveoli at the end of the smallest air passages (bronchioles) of the lungs are destroyed and hyperinflated. Chronic bronchitis is inflammation of the lining of the bronchial tubes,  characterized by daily cough and mucus (sputum) production. See Figure 5.3a for an illustration of normal lungs compared to lungs with COPD.

Figure 5.3b Normal lungs compared with lungs in a person with COPD

COPD is treatable but not curable. COPD symptoms often don’t appear until significant lung damage has occurred, and they usually worsen over time, particularly if smoke exposure continues.

Other signs and symptoms of COPD may include:

• Shortness of breath, especially during physical activities
• Wheezing
• Chest tightness
• Chronic cough that may produce mucus (sputum) that may be clear, white, yellow, or greenish
• Cyanosis
• Frequent respiratory infections
• Lack of energy
• Unintended weight loss (in later stages)

Unlike some diseases, COPD has a clear cause and a clear path of prevention. The majority of cases are directly related to cigarette smoking, and the best way to prevent COPD is to never smoke — or to teach clients to stop smoking now.

Image Descriptions

Figure 5.3a How Asthma Affects the Airway –  Image Description

A normal airway has relaxed smooth muscles. Asthmatic airway has relaxed smooth muscles with inside wall inflamed and thickened. During an asthma attack, air is trapped in alveoli and the smooth muscles tighten.

[Return to Figure 5.3a]

Clinical Reasoning and Decision-Making Related to Gas Exchange

Clinical reasoning is a way that we think and process our knowledge, including what we have read or learned in the past, and apply it to the current context of what we are seeing right now in practice Nurses make decisions all the time, and making decisions requires a complex thinking process. There are so many useful tools to be found online that can support your thinking through to clinical judgments. In the past, and still relevant, is the nursing process.  We will utilize the nursing process as well as clinical judgment tools to help you clearly understand further respiratory drugs and their application in practice.

Now that we have reviewed the respiratory system and common respiratory disorders, let’s apply your knowledge to support the learning of the respiratory system and drugs related to gas exchange.

Assessment

Although there are numerous details to consider when administering medications, it is always important to first think about what you are giving and why.

First, let’s think of why? Recognizing Cues

Respiratory medications are often given to alleviate allergies or cold symptoms, or to decrease/eliminate shortness of breath (SOB). An important piece of your nursing assessment should be to assess the client’s respiratory status. The respiratory assessment includes observing the respiratory rate and quality of respirations (shallow, deep), obtaining a pulse oximetry reading, and auscultating lung sounds. Other pieces of the assessment include inspecting skin color, such as observing for pallor, or cyanosis, and determining if there is a cough or sputumpresent. If sputum is present, it should be assessed for color, odor, consistency, and amount (COCA).

Additional baseline information to collect prior to the administration of any respiratory medication includes any history of allergy or previous adverse drug response.

Interventions

Next, plan (refine your hypothesis), and take action.

Respiratory medications are available in many different formulations, such as nasal spray, inhalations, oral tablets or liquids, injections, or intravenous route, so it is always important to verify the correct route and anticipate the associated side effects. For example, inhalations deliver the required medicine or medicines directly to the lungs, which means the medicine(s) can act directly on the lung tissues, minimizing systemic side effects. On the other hand, intravenous medications are administered to act quickly, but can cause systemic side effects. Additionally, some products contain more than one medicine with different dosages (for example, inhalers that combine a long-acting bronchodilator with a glucocorticoid).

During the administration of respiratory medications, it is important to anticipate the expected outcome of the medication and any common side effects. For example, albuterol is a short acting Beta-2 agonist that is given for bronchodilation. The nurse should plan to perform a respiratory assessment before and after administration of albuterol to document the effectiveness of the medication, as well as monitor for tachycardia, a common side effect.

Additionally, the nurse should also ensure the proper use of the inhalers by the client. Observe the client self-administering the medication, and further instruct the client in proper use.

Evaluation

Finally, evaluate the outcomes of your action.

It is important to always evaluate the client’s response to a medication. With respiratory medications, the nurse should assess decrease in allergy symptoms (cough, runny nose, tearing eyes) and any decrease in shortness of breath. The nurse should complete a respiratory assessment (respirations, pulse oximetry, and lung auscultation) before and after the medications have been administered and compare the results. If the symptoms are not improving or the clinical assessment is worsening, prompt intervention is required (such as notification of the health care provider for further orders) to prevent further clinical deterioration. Utilizing tools such as this concept map helps work through thinking like a nurse. This map in figure 5.4 is an example of what a concept map could look like. Your own design may vary so do not worry. You should now take time to explore what you have read and apply it visually.

Figure 5.4 Concept Map of Gas Exchange [Image Description]

Image Description

Figure 5.4 Concept Map of Gas Exchange image description: This concept map illustrates the steps of gas exchange. The flow is as follows:

• Respirations
  • Inhalation of air
• Expiration to atmosphere
• Alveoli
  • Pulmonary capillaries
  • Diffusion
  • Hemoglobin carrying capacity
    • Perfusion
    • Delivery of oxygen and nutrients
  • Cells lining alveoli
• Cellular uptake of oxygen and nutrients
• Cellular metabolism and energy
  • Waste products – carbon dioxide
  • Capillaries carrying waste out of cell through perfusion
    • Expiration [Return to image]

Now that we have reviewed basic concepts, we will take a closer look at specific respiratory classifications  and specific administration considerations, therapeutic effects, adverse/side effects, and teaching needed for each class of medications.

Administration Considerations

Drugs related to gas exchange are given through multiple routes including inhalation, oral, sublingual, injectable, and nebulized.  It is important to consider how these routes are impacted by your client’s needs. For example, children may struggle with certain routes such as inhalation.  As a nurse, you must anticipate the needs of your client and mitigate complications. In this example, the nurse can provide an aerosol chamber to support the client getting the proper medication.

Therapeutic Effects

Nurses are responsible for monitoring the effects of any medications we administer. The therapeutic effect is the result we expect to see from administering a drug.  In the next few chapters, you will learn about different drugs used for clients and the therapeutic effect of each drug. It is important to note that since we are discussing respiratory drugs, likely one of the therapeutic effects will be improved breathing.

Adverse and Side Effects

Side effects are the negative consequence of taking medications.  It is important that nurses understand what side effects may occur and try to prevent these from happening. Adverse effects and side effects must be considered when deciding to take a medication. The benefit of the medication must out weigh the negative effects.

Client Teaching

Health Literacy is an important concept in medication administration and the nurse’s role.  We must ensure our clients are comfortable and confident in the medication process and their knowledge about the medications they are taking. Before discharging a client from care, the nurse should ensure that the client fully understands their medications, how to take them, side effects that might happen, and the therapeutic effects we expect to see.

In the next chapters we will look at drug classifications related to gas exchange.

Antihistamines

Diphenhydramine and Cetirizine are two commonly-seen antihistamine drugs. In this chapter we explore Diphenhydramine.

Diphenhydramine is an example of a first-generation antihistamine. (See Figures 5.6a and 5.6b.)  Second-generation antihistamines were developed to have fewer side effects. An example of a second-generation antihistamine is cetirizine.

Figure 5.6a Diphenhydramine is a first-generation antihistamine that is available orally or as an IV medication

Figure 5.6b Diphenhydramine HCl preparation, single dose vial for IV administration

Mechanism of Action

Antihistamines have the following mechanisms of action: blocks histamine at H1 receptors; inhibits smooth muscle constriction in blood vessels and the respiratory and GI tracts; and decreases capillary permeability, salivation, and tear formation.

Indications for Use

Antihistamines are used for relief of allergy or cold symptoms.

Nursing Considerations Across the Lifespan

This medication is not safe for children under the age of 2 years without a healthcare provider’s order.

Adverse/Side Effects

First-generation medications can cause anticholinergic effects (such as dry mouth, urinary retention, constipation and blurred vision). CNS depression or CNS stimulation with excessive doses can occur, especially in children. Therefore, first-generation antihistamines should be used with caution in the elderly.

Second-generation medications may cause headache, nausea, vomiting, dysmenorrhea, and fatigue.

Client Teaching & Education

Clients should be advised that antihistamines may cause drowsiness, and concurrent use of alcohol or other CNS depressants should be avoided.  Clients should take only the recommended amount of medication and not exceed dosing recommendations.  Some clients may experience side effects such as dry mouth, and frequent oral hygiene may assist in alleviating discomfort.

Diphenhydramine Medication Card

Now let’s take a closer look at the medication card for diphenhydramine and cetirizine in Table 5.6., , Medication cards are intended to assist students to learn key points about each medication class.  Basic information related to a common generic medication in this class is outlined, including administration considerations, therapeutic effects, and side effects/adverse effects.  Prototype/generic medication listed in the medication card is also hyperlinked to a free resource from  Daily Med.  Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.

Decongestants

Decongestant medications have been available over the counter (drugs that you can buy at a pharmacy without a prescription) for years.  Although they are readily available, considerations are necessary when taking any drug. In this chapter we will explore these drugs further.

Pseudoephedrine

Pseudoephedrine is an over-the-counter (OTC) decongestant (see Figure 5.7). More details regarding pseudoephedrine are described in the “Autonomic Nervous System” chapter.

Mechanism of Action

Pseudoephedrine acts directly on the adrenergic receptors and acts indirectly by releasing norepinephrine from its storage sites. The drug produces vasoconstriction, which shrinks nasal mucosa membranes.

Indications for Use

Decongestants relieve nasal obstruction due to inflammation.

Nursing Considerations Across the Lifespan

This medication is not safe for children under the age of 4 years.

Adverse/Side Effects

Common adverse/side effects include hypertension, dysrhythmia, dizziness, headache, insomnia, and restlessness. Some clients may experience blurred vision, tinnitus, chest tightness, dry nose, and nasal congestion.

Decongestants are contraindicated in clients with severe hypertension, coronary artery disease (CAD), narrow-angle glaucoma, and some antidepressant use. Also, clients who have cardiac dysrhythmias, hyperthyroidism, DM (diabetes mellitus), prostatic hypertrophy, and glaucoma should use with caution.

Client Teaching & Education

Client must take care to follow dosing recommendations.  If dosing standards are surpassed, some clients may experience side effects such as increased nervousness, breathing difficulties, heart rate changes, and hallucinations.

Pseudoephedrine Medication Card

Now let’s take a closer look at the medication drug card on Pseudoephedrine. Medication cards are intended to assist students to learn key points about each medication class.  Basic information related to a common generic medication in this class is outlined, including administration considerations, therapeutic effects, and side effects/adverse effects.  Prototype/generic medication listed in the medication card is also hyperlinked to a free resource from Daily Med.  Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.in Table 5.7., , .

Antitussives

Antitussives are frequently used to prevent cold and flu symptoms. In this chapter, we will review one commonly used specific antitussive called Dextromethorphan.

Dextromethorphan is an example of an antitussive (see Figure 5.8).

Figure 5.8: Robitussin Cough Cold Flu Congestion decongestant Relief Medicine

Mechanism of Action

Dextromethorphan suppresses a cough by depressing the cough center in the medulla oblongata or the cough receptors in the throat, trachea, or lungs, effectively elevating the threshold for coughing.

Indication for Use

Antitussives are used for a dry, hacking, nonproductive cough that interferes with rest and sleep.

Nursing Considerations Across the Lifespan

This medication is not safe for children under the age of 4 years.

Adverse/Side Effects

The most common side effects include nausea and drowsiness. Some clients may experience a rash or difficulty breathing. High doses may cause hallucinations and disassociation, and the drug has been reported to be used as a recreational drug.

Client Teaching & Education

Clients should take care to avoid irritants that stimulate their cough.  Additionally, antitussive medications can cause drowsiness, and clients should avoid taking them with other CNS depressants or alcohol.

Dextromethorphan Medication Card

Now let’s take a closer look at the medication card on dextromethorphan., ,

Expectorants

Guaifenesin (Mucinex) is an example of an expectorant.

Mechanism of Action

Expectorants reduce the viscosity of tenacious secretions by irritating the gastric vagal receptors that stimulate respiratory tract fluid, thus increasing the volume but decreasing the viscosity of respiratory tract secretions.

Indication for Use

Expectorants are used for a productive cough and for loosening mucus from the respiratory tract.

Nursing Considerations Across the Lifespan

The medication is safe for all ages. Guaifenesin is only recommended for use during pregnancy and breastfeeding when the benefit outweighs the risk.

Adverse/Side Effects

Guaifenesin may cause a skin rash, headache, nausea, and vomiting.

Client Teaching & Education

Clients should take care to avoid irritants that stimulate their cough.  Additionally, the medication can cause drowsiness. Clients should avoid taking them with other CNS depressants or alcohol.

Guaifenesin Medication Card

Now let’s take a closer look at the medication card for guaifenesin.,,