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Questions and Answers
What is the effect of increased gastric pH on enteric-coated medications?
What is the effect of increased gastric pH on enteric-coated medications?
Which type of drugs is affected by the decrease in plasma albumin levels?
Which type of drugs is affected by the decrease in plasma albumin levels?
What is the effect of age-related changes on the distribution of lipophilic drugs?
What is the effect of age-related changes on the distribution of lipophilic drugs?
Why do older adults have a higher susceptibility to side-effects of certain medications?
Why do older adults have a higher susceptibility to side-effects of certain medications?
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What is the effect of age-related changes on the liver?
What is the effect of age-related changes on the liver?
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What is the effect of age-related changes on the absorption of calcium carbonate?
What is the effect of age-related changes on the absorption of calcium carbonate?
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Why do older adults require a reduced loading dose of digoxin?
Why do older adults require a reduced loading dose of digoxin?
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What is the effect of age-related changes on the binding of basic drugs?
What is the effect of age-related changes on the binding of basic drugs?
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Which drug requires dose reduction in elderly patients due to its active metabolites?
Which drug requires dose reduction in elderly patients due to its active metabolites?
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Which equation is used to calculate the estimated glomerular filtration rate (eGFR)?
Which equation is used to calculate the estimated glomerular filtration rate (eGFR)?
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Why may creatinine levels not accurately reflect renal function in elderly patients?
Why may creatinine levels not accurately reflect renal function in elderly patients?
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Which of the following drugs is a prodrug?
Which of the following drugs is a prodrug?
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What is the consequence of acute illness on renal function?
What is the consequence of acute illness on renal function?
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Why should eGFR not be used for patients at extremes of body weight?
Why should eGFR not be used for patients at extremes of body weight?
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What is the consequence of reduced hepatic blood flow in patients with heart failure on hepatic metabolism of drugs?
What is the consequence of reduced hepatic blood flow in patients with heart failure on hepatic metabolism of drugs?
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What can be used to estimate creatinine clearance (CrCl)?
What can be used to estimate creatinine clearance (CrCl)?
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Which of the following drugs is likely to have a higher than expected plasma level in an elderly patient due to decreased lean body mass?
Which of the following drugs is likely to have a higher than expected plasma level in an elderly patient due to decreased lean body mass?
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Which enzymatic activity is decreased in the liver of an elderly patient, leading to decreased metabolism of certain drugs?
Which enzymatic activity is decreased in the liver of an elderly patient, leading to decreased metabolism of certain drugs?
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What is the expected effect of decreased gastric pH on enteric-coated aspirin in an elderly patient?
What is the expected effect of decreased gastric pH on enteric-coated aspirin in an elderly patient?
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Which of the following drugs is likely to have an increased free fraction available in an elderly patient due to decreased serum albumin?
Which of the following drugs is likely to have an increased free fraction available in an elderly patient due to decreased serum albumin?
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What is the expected effect of decreased liver mass and blood flow on the metabolism of certain drugs in an elderly patient?
What is the expected effect of decreased liver mass and blood flow on the metabolism of certain drugs in an elderly patient?
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Which of the following drugs is likely to accumulate in an elderly patient due to decreased glomerular filtration rate?
Which of the following drugs is likely to accumulate in an elderly patient due to decreased glomerular filtration rate?
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Study Notes
Pharmacokinetic Changes in the Older Person
- Older adults experience significant pharmacokinetic and pharmacodynamic changes due to advanced age.
- These changes affect how the body handles drugs, including absorption, distribution, metabolism, and elimination.
Absorption
- Increased gastric pH is a characteristic of aging, which can affect the absorption of certain drugs.
- Decreased gastric emptying in older adults increases the risk of gastrointestinal adverse effects.
- Calcium carbonate, iron salts, and vitamin B12 require an acidic environment for absorption.
- Intestinal absorption is usually not affected.
Distribution
- The relative increase in body fat and decrease in water leads to changes in drug distribution.
- The volume of distribution of lipophilic drugs increases, causing accumulation of drugs like benzodiazepines.
- The volume of distribution of hydrophilic drugs decreases, requiring a reduced loading dose for drugs like digoxin.
- Acidic drugs bind to albumin, and basic drugs bind to α1-acid glycoprotein.
- Plasma albumin levels decrease, increasing the free fraction of acidic drugs like furosemide, phenytoin, and warfarin.
Metabolism
- The liver becomes less efficient at breaking down many drugs due to reduced liver mass and blood flow.
- Other factors influencing hepatic metabolism include smoking, heart failure, and enzyme-inducing or inhibiting drugs.
- Conversions of prodrugs, like simvastatin, are less efficient in older people.
- Dose reduction of 40% is recommended for atorvastatin in the elderly.
Elimination
- Acute illness can lead to rapid decreases in renal function, making established drugs toxic.
- Each stage of chronic kidney disease (CKD) is defined by the patient's estimated glomerular filtration rate (eGFR).
- Renal function generally declines with age, and many elderly patients have a GFR < 50 mL/min.
- Creatinine clearance (CrCl) should be calculated using the Cockcroft-Gault equation, especially for patients at extremes of body weight.
- Renal impairment affects drug choice, and eGFR should be corrected to the actual GFR for patients with narrow therapeutic windows.
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Description
Learn about the pharmacokinetic changes that occur with advanced age, including how the body handles drugs, and how individual physiology can vary. Understand the effects of aging on drug absorption, distribution, metabolism, and elimination.
