CNS Pharmacology USMLE Step 1 Practice Question
A 45-year-old woman with moderate osteoarthritis presents with knee pain (7/10). Vital signs: BP 128/82, HR 82, RR 16, Temp 37.2°C, SpO2 98%. Her rheumatologist compares two experimental analgesics in clinical trials. Drug X produces greater maximal pain relief than drug Y, reducing her pain to 2/10 at higher doses. However, drug Y achieves 50% of its maximum effect at a substantially lower dose. She denies nausea or drowsiness with either agent. Which pharmacokinetic property best distinguishes drug X from drug Y?
Answer choices
- AHigher efficacy and lower potencyCorrect answer
- BHigher potency and lower efficacy
- CLower bioavailability and higher volume of distribution
- DHigher therapeutic index and lower clearance
- ENoncompetitive antagonism with increased receptor number
- FLower affinity for the target receptor and increased hepatic metabolism
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