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Smoking cessation and theophylline — GPhC CRA MCQ

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HardRespiratory TherapeuticsSmoking cessation and theophyllineGPhC CRA

A 55-year-old man with COPD takes theophylline modified-release and has stopped smoking with varenicline. He asks why the respiratory nurse arranged a blood test after he quit. What is the most important interaction to flag?

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Correct answer: B — Stopping smoking can increase theophylline levels

Tobacco smoke induces hepatic metabolism of theophylline. When smoking stops, theophylline clearance can fall and toxicity risk can increase. Monitoring and dose adjustment may be required. This is related to smoke exposure rather than nicotine replacement itself.

Reference: https://www.pharmacyregulation.org/registration-assessment#stage-8-order-30