{"id":40,"date":"2019-09-18T16:00:13","date_gmt":"2019-09-18T20:00:13","guid":{"rendered":"https:\/\/opentextbc.ca\/nursingpharmacology\/chapter\/1-6-excretion\/"},"modified":"2023-03-03T12:42:13","modified_gmt":"2023-03-03T17:42:13","slug":"1-6-excretion","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/nursingpharmacology\/chapter\/1-6-excretion\/","title":{"raw":"1.6 Phamacokinetics \u2013 Excretion","rendered":"1.6 Phamacokinetics \u2013 Excretion"},"content":{"raw":"[pb_glossary id=\"564\"]Excretion[\/pb_glossary] 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.\r\n
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Clinical Reasoning and Decision Making Activity 1.6<\/p>\r\n\r\n<\/header>\r\n

\r\n\r\n\"\"When providing care for a client who has chronic kidney disease, how does this disease impact medication excretion?\r\n\r\nNote: Answers to these can be found in the \"Answer Key<\/a>\" sections at the end of the book.\r\n\r\n<\/div>\r\n<\/div>\r\n

Routes of Excretion<\/h1>\r\nNow let's further discuss the various routes of excretion from the body.\r\n

Kidney<\/h2>\r\nThe most common route of excretion is the kidney.\u00a0 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:\u00a0 age, weight, biological sex, and kidney function.\u00a0 Kidney function is measured by lab values such as serum creatinine, glomerular filtration rate (GFR), and creatinine clearance.\u00a0 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.\r\n

Liver<\/h2>\r\nAs 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.\u00a0 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.\r\n

Other Routes to Consider<\/h1>\r\nSweat, 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.\r\n

Putting it all together\u2026<\/h1>\r\nPrescribing and administering medications in a safe manner to clients is challenging and requires a team effort by pharmacists, healthcare providers, and nurses.\u00a0 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.\r\n

Lifespan Considerations<\/h1>\r\nNeonate & Pediatrics:<\/strong> 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.\u00a0 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.\u00a0 Therefore, frequent assessment of infants and children is vital for the early identification of drug toxicity.[footnote]Fernandez, E., Perez, R., Hernandez, A., Tejada, P., Arteta, M., & Ramos, J. T. (2011). Factors and mechanisms for pharmacokinetic differences between pediatric population and adults. Pharmaceutics, 3<\/em>(1), 53\u201372. https:\/\/doi.org\/10.3390\/pharmaceutics3010053<\/a>[\/footnote]\r\n\r\nOlder Adult:<\/strong>\u00a0 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.\u00a0 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.\"[footnote]Fernandez, E., Perez, R., Hernandez, A., Tejada, P., Arteta, M., & Ramos, J. T. (2011). Factors and mechanisms for pharmacokinetic differences between pediatric population and adults. Pharmaceutics, 3<\/em>(1), 53\u201372. https:\/\/doi.org\/10.3390\/pharmaceutics3010053<\/a>[\/footnote]\r\n
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\u00a0Interactive Activity<\/h3>\r\n[h5p id=\"2\"]\r\n\r\n<\/div>\r\n

Attributions<\/h3>\r\n