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Theophylline toxicity — GPhC CRA MCQ

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HardRespiratory TherapeuticsTheophylline toxicityGPhC CRA

A woman aged 62 years takes theophylline modified-release 300mg twice daily and has stopped smoking after a hospital admission for pneumonia. She now reports nausea, tremor and palpitations; her discharge medicines also include clarithromycin. What is the most important interaction to flag?

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Correct answer: B — Theophylline toxicity risk is increased by smoking cessation and clarithromycin

Smoking induces theophylline metabolism, so stopping smoking can raise theophylline concentrations. Clarithromycin can also increase theophylline exposure and toxicity risk. Nausea, tremor and palpitations are concerning for theophylline toxicity and require urgent prescriber review. This scenario requires integrating symptoms, medicine changes and smoking status.

Reference: BNF