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Theophylline macrolide interaction — GPhC CRA MCQ

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HardRespiratory TherapeuticsTheophylline macrolide interactionGPhC CRA

A patient stabilised on theophylline is prescribed clarithromycin for a chest infection. They report nausea with previous antibiotic courses. What is the most important interaction to flag?

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Correct answer: D — Increased theophylline concentration and toxicity risk

Macrolides such as clarithromycin can increase theophylline exposure and toxicity risk. The prescription should be queried or monitoring arranged before supply. In this scenario, the correct option is increased theophylline concentration and toxicity risk. The other options are plausible but do not address the key clinical, legal or safety issue as directly. This aligns with UK pharmacy practice guidance cited in the reference field.

Reference: BNF; Stockley's Drug Interactions