Theophylline and clarithromycin — GPhC CRA MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: D — Query clarithromycin and arrange a theophylline level and toxicity review
Query clarithromycin and arrange a theophylline level and toxicity review: Clarithromycin can reduce theophylline clearance; nausea may be an early concentration-related adverse effect and the narrow therapeutic index warrants action. Supply both medicines and increase theophylline during infection with level monitoring: Increasing the dose would amplify the toxicity risk. Supply both medicines with administration separated by at least two hours: The interaction is metabolic and is not reliably prevented by dose separation. Change to immediate-release theophylline at the same total daily dose: Formulation substitution does not remove the interaction and can alter exposure. Reassure and continue both medicines with the existing monitoring schedule: The concern is increased, not reduced, theophylline exposure.
Reference: BNF: theophylline: https://bnf.nice.org.uk/drugs/theophylline/; BNF: clarithromycin: https://bnf.nice.org.uk/drugs/clarithromycin/