CNS Pharmacology USMLE Step 1 Practice Question
A 58-year-old woman with chronic osteomyelitis has been receiving intravenous vancomycin for 10 days, with a trough level of 18 mcg/mL. Her temperature is 37.8°C, blood pressure is 132/84 mmHg, and serum creatinine has risen acutely from 0.9 to 3.2 mg/dL, consistent with acute kidney injury. Urinalysis shows granular casts. Her plasma drug level remains within the therapeutic range, but the team is concerned about progressive toxicity. To maintain therapeutic drug concentrations without further nephrotoxicity, which of the following parameters should be adjusted most directly?
Answer choices
- ADecrease potency by adding a competitive antagonist
- BIgnore the change because half-life is unrelated to renal function
- CIncrease bioavailability by changing to oral therapy
- DDecrease the maintenance dose because clearance has fallenCorrect answer
- EIncrease the loading dose because volume of distribution has fallen
- FIncrease the dosing interval while maintaining the same dose because renal clearance has decreased
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