Altered pharmacokinetics in elderly patients and dosing MCQs With Answer

Introduction: This quiz collection focuses on altered pharmacokinetics in elderly patients and dosing considerations—an essential topic for M.Pharm students studying Clinical Pharmacokinetics and Therapeutic Drug Monitoring. Aging produces predictable changes in absorption, distribution, metabolism and excretion that alter drug exposure, therapeutic response and toxicity risk. Understanding body-composition shifts, protein binding changes, reduced hepatic and renal clearance, and altered pharmacodynamics allows rational dose adjustments, proper selection of drugs and interpretation of therapeutic drug monitoring. These MCQs emphasize mechanistic insights, clinically relevant calculations, monitoring strategies and common pitfalls encountered when prescribing for older adults to prepare you for exams and clinical decision-making.

Q1. Which age-related change most commonly increases the volume of distribution (Vd) for lipophilic drugs in elderly patients?

• Decrease in total body fat
• Increase in total body water
• Increase in body fat proportion
• Increase in plasma albumin concentration

Correct Answer: Increase in body fat proportion

Q2. How does hypoalbuminemia in elderly patients typically affect the pharmacokinetics of highly albumin-bound acidic drugs?

• Decreased free fraction and reduced effect
• Increased free fraction leading to greater pharmacologic effect and toxicity
• No change in free fraction but increased hepatic clearance
• Increased total concentration with no change in free drug

Correct Answer: Increased free fraction leading to greater pharmacologic effect and toxicity

Q3. Which component of hepatic drug metabolism is most affected by aging?

• Phase II conjugation reactions (e.g., glucuronidation)
• Phase I oxidative reactions (e.g., CYP-mediated metabolism)
• Renal excretion of metabolites
• Active tubular secretion

Correct Answer: Phase I oxidative reactions (e.g., CYP-mediated metabolism)

Q4. For drug dosing adjustments in elderly patients with reduced renal function, which equation is most commonly used by clinicians to estimate creatinine clearance for dosing?

• MDRD (Modification of Diet in Renal Disease) formula
• CKD-EPI equation
• Cockcroft–Gault equation
• Measured cystatin C only

Correct Answer: Cockcroft–Gault equation

Q5. What is the expected effect on elimination half-life (t1/2) for drugs cleared predominantly by the kidney when glomerular filtration declines with age?

• t1/2 is decreased, resulting in subtherapeutic levels
• t1/2 is unchanged because volume of distribution compensates
• t1/2 is increased, raising risk of accumulation
• t1/2 fluctuates unpredictably with no clinical consequence

Correct Answer: t1/2 is increased, raising risk of accumulation

Q6. In an elderly patient with increased Vd for a lipophilic antibiotic and decreased clearance, what is the most rational dosing strategy?

• Increase both loading and maintenance doses
• Increase loading dose but decrease maintenance dose or prolong dosing interval
• Decrease loading dose and increase maintenance dose
• No change in dosing required

Correct Answer: Increase loading dose but decrease maintenance dose or prolong dosing interval

Q7. Which statement best describes warfarin management in the elderly?

• Elderly require higher warfarin doses due to increased clearance
• Hypoalbuminemia decreases free warfarin and reduces anticoagulant effect
• Elderly are more sensitive to warfarin; lower initial doses and careful INR monitoring are needed
• Warfarin dosing is unaffected by age-related changes in pharmacokinetics

Correct Answer: Elderly are more sensitive to warfarin; lower initial doses and careful INR monitoring are needed

Q8. Digoxin dosing in elderly patients with reduced renal function typically requires which adjustment?

• Increase loading and maintenance doses due to increased Vd
• No dose change but double the dosing frequency
• Reduce maintenance dose and/or extend dosing interval; monitor serum levels
• Stop monitoring levels because total concentrations are reliable

Correct Answer: Reduce maintenance dose and/or extend dosing interval; monitor serum levels

Q9. In elderly patients with low muscle mass and near-normal serum creatinine, which approach improves estimation of renal function for drug dosing?

• Rely solely on serum creatinine value
• Use cystatin C–based GFR estimation or measured creatinine clearance
• Use age alone to estimate GFR
• Assume normal renal function unless symptomatic

Correct Answer: Use cystatin C–based GFR estimation or measured creatinine clearance

Q10. Phenytoin is highly protein bound. In an elderly patient with low albumin, which approach gives the most accurate assessment to avoid toxicity?

• Measure total plasma phenytoin concentration only
• Use the albumin-corrected phenytoin formula or measure free phenytoin concentration
• Assume lower total concentration equals safety and increase dose
• Stop phenytoin and use phenobarbital instead

Correct Answer: Use the albumin-corrected phenytoin formula or measure free phenytoin concentration

Q11. Which class of drugs has decreased oral absorption in elderly patients due to increased gastric pH (less acidic stomach)?

• Drugs requiring an acidic environment for dissolution (e.g., ketoconazole)
• Highly water-soluble drugs absorbed in stomach
• All beta-lactam antibiotics
• Intravenous drugs administered orally

Correct Answer: Drugs requiring an acidic environment for dissolution (e.g., ketoconazole)

Q12. How does decreased hepatic blood flow in the elderly affect high hepatic extraction ratio drugs (e.g., propranolol, morphine)?

• Clearance increases and oral bioavailability decreases
• Clearance decreases and oral bioavailability increases
• Clearance is unchanged because hepatic extraction is flow-independent
• Only phase II metabolism is affected, not extraction

Correct Answer: Clearance decreases and oral bioavailability increases

Q13. Which of the following drug classes commonly requires therapeutic drug monitoring (TDM) in elderly patients due to narrow therapeutic index and altered PK?

• Statins
• Aminoglycoside antibiotics
• Oral contraceptives
• Topical corticosteroids

Correct Answer: Aminoglycoside antibiotics

Q14. Calculate the Cockcroft–Gault estimated creatinine clearance for a 75-year-old male, weight 70 kg, serum creatinine 1.2 mg/dL. (Use formula: CrCl = (140 − age) × weight / (72 × SCr)).

• Approximately 38 mL/min
• Approximately 53 mL/min
• Approximately 72 mL/min
• Approximately 25 mL/min

Correct Answer: Approximately 53 mL/min

Q15. Which benzodiazepine is most likely to accumulate in elderly patients due to high lipophilicity and large Vd?

• Lorazepam (less lipophilic)
• Oxazepam (shorter-acting)
• Diazepam (highly lipophilic, long-acting)
• Temazepam (intermediate)

Correct Answer: Diazepam (highly lipophilic, long-acting)

Q16. For aminoglycoside dosing in elderly patients with reduced renal clearance, which dosing approach is often preferred to minimize toxicity while maintaining efficacy?

• Decrease dose but maintain the same dosing interval
• Increase dose and shorten dosing interval
• Use extended (longer) dosing intervals while keeping peak-target doses and monitor troughs
• Abolish therapeutic drug monitoring because it is unreliable

Correct Answer: Use extended (longer) dosing intervals while keeping peak-target doses and monitor troughs

Q17. When hypoalbuminemia increases the free fraction (fu) of a low-extraction, highly protein-bound drug and intrinsic clearance is unchanged, what is the likely effect on free (unbound) drug concentration and hepatic clearance?

• Free concentration decreases and hepatic clearance decreases
• Total concentration increases but free concentration unchanged
• Free concentration increases; hepatic clearance may increase proportionally for low-extraction drugs
• No change in pharmacologic effect

Correct Answer: Free concentration increases; hepatic clearance may increase proportionally for low-extraction drugs

Q18. A lipophilic drug has a target plasma concentration of 10 mg/L. In an elderly patient the apparent Vd is estimated at 1.2 L/kg and body weight is 70 kg. Calculate the loading dose (assuming F = 1).

• 84 mg
• 840 mg
• 1200 mg
• 700 mg

Correct Answer: 840 mg

Q19. Which type of Phase II metabolic reaction is relatively preserved in elderly patients compared with Phase I reactions?

• Oxidation
• Reduction
• Glucuronidation (conjugation)
• CYP3A4-mediated hydroxylation

Correct Answer: Glucuronidation (conjugation)

Q20. For concentration-dependent antibiotics like aminoglycosides, which PK/PD index best predicts efficacy and should guide dosing in elderly patients?

• Time above MIC (T>MIC)
• Area under the curve to MIC ratio (AUC/MIC)
• Peak concentration to MIC ratio (Cmax/MIC)
• Trough concentration only

Correct Answer: Peak concentration to MIC ratio (Cmax/MIC)

Download