Beta Blockers USMLE Step 1 Practice Question
A 67-year-old man with atrial fibrillation presents with heart rate 52 bpm, blood pressure 98/62 mmHg, and respiratory rate 16/min. He takes digoxin and metoprolol. Recent serum digoxin level is 2.1 ng/mL (therapeutic range 0.8–2.0). He reports nausea and blurred vision but denies palpitations. EKG shows prolonged PR interval without heart block. His physician recognizes these symptoms reflect digoxin toxicity. Which pharmacologic property necessitates close monitoring of serum digoxin concentrations in patients receiving concurrent beta-blockers?
Answer choices
- AHigh volume of distribution
- BZero order metabolism at baseline doses
- CLow potency
- DLow therapeutic indexCorrect answer
- EHigh efficacy
- FExtensive first-pass hepatic metabolism
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