Pharmacology · single question
A 90-year-old patient taking multiple medications is prescribed antibiotics. What physiologic change most affects dosing?
Show answer and explanation
Correct answer: A. Decreased glomerular filtration rate (GFR)
Decreased GFR is the critical age-related change. Renal clearance declines with age, causing drug accumulation at standard doses.
- A. ✅ CORRECT – GFR decreases ~1 mL/min/year after age 40; significantly affects antibiotic clearance.
- B. ❌ Hepatic enzyme activity typically decreases with age.
- C. ❌ Protein binding may decrease with age but GFR is the dominant dosing concern.
- D. ❌ Gastric acid production decreases with age (achlorhydria).