Pharmacokinetic Parameters Practice Test

A 68-year-old male (weight 78 kg, height 175 cm) with community-acquired pneumonia is started on levofloxacin. Current medications: lisinopril 20 mg PO daily, atorvastatin 40 mg PO nightly, aspirin 81 mg PO daily. Medical history: hypertension, hyperlipidemia, chronic kidney disease stage 3. Allergies: penicillin (rash). Labs: serum creatinine 2.0 mg/dL (high; normal 0.7–1.3), AST 22 units/L, ALT 25 units/L. Using Cockcroft–Gault with actual body weight, how should the levofloxacin dosage be adjusted for this patient's renal function if the usual dose is 750 mg PO every 24 hours?

A 63-year-old man (weight 70 kg, height 172 cm) with MRSA bacteremia is on vancomycin. Current medications: vancomycin 1,000 mg IV every 12 hours, amlodipine 10 mg PO daily. Medical history: hypertension, chronic kidney disease stage 3. Allergies: none. Labs: SCr 1.8 mg/dL. A vancomycin trough drawn appropriately before the 5th dose is 8 mg/L (goal trough 15–20 mg/L for this infection per institutional protocol). Assuming linear kinetics, what is the best maintenance dose adjustment to achieve the target trough?