CNS Pharmacology USMLE Step 1 Practice Question
A 71-year-old man with Alzheimer disease has taken donepezil 10 mg daily for 4 weeks. He presents with syncope, BP 98/62 mmHg, HR 48 bpm, RR 16, and SpO2 98% on room air. ECG shows a prolonged PR interval of 220 ms consistent with first-degree heart block. Physical exam reveals hyperactive bowel sounds. His wife reports increased social withdrawal and persistent nausea with two episodes of vomiting. Recent labs show normal electrolytes, normal troponin, and no QTc prolongation. He denies chest pain. Which of the following best explains these complications?
Answer choices
- AAnticholinergic rebound from abrupt dose escalation
- BAcetylcholinesterase inhibition causing excessive cholinergic activity at cardiac and GI sitesCorrect answer
- CAmyloid-beta deposition in the myocardium
- DDonepezil accumulation from renal insufficiency
- EQT prolongation from hepatotoxicity
- FSelective serotonin reuptake inhibitor interaction potentiating cardiac conduction abnormalities
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