skip to main content

Theophylline and macrolide interaction — GPhC CRA MCQ

Instant feedback + full explanation. One question, done properly.

HardRespiratory TherapeuticsTheophylline and macrolide interactionGPhC CRA

A 59-year-old woman with COPD takes modified-release theophylline 300mg twice daily. She presents a prescription for clarithromycin 500mg twice daily for a chest infection. She reports nausea and palpitations during previous antibiotic courses, and her last theophylline level was near the upper end of the target range. What is the most important interaction to flag?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Clarithromycin may increase theophylline toxicity

Macrolides can increase theophylline concentrations and toxicity risk, with symptoms such as nausea, tremor, palpitations and seizures. The history and previous high level make this especially important. The prescriber should be contacted for an alternative antibiotic or monitoring plan. The other options do not represent the key interaction.

Reference: BNF Theophylline interactions; NICE CKS COPD