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Digoxin toxicity — GPhC CRA MCQ

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HardCardiovascular TherapeuticsDigoxin toxicityGPhC CRA

A patient stabilised on clozapine 400 mg daily is admitted to a smoke-free ward and stops smoking abruptly. Five days later he develops marked sedation, hypersalivation and myoclonus. What is the most appropriate pharmacy action?

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Correct answer: D — Arrange urgent clozapine review and plasma-level assessment

Polycyclic aromatic hydrocarbons in tobacco smoke induce CYP1A2; nicotine itself is not responsible. Abrupt smoking cessation can therefore increase clozapine exposure within days and cause dose-related toxicity. Urgent clinical review, plasma-level assessment and dose adjustment are needed. Carbamazepine is inappropriate because of marrow toxicity and important interactions.

Reference: https://www.pharmacyregulation.org/students-and-trainees/pharmacist-education-and-training/registration-assessment