Simvastatin and amlodipine — GPhC CRA MCQ
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Correct answer: A — Query and reduce simvastatin to no more than 20 mg daily
Query and reduce simvastatin to no more than 20 mg daily: Amlodipine increases simvastatin exposure and myopathy risk; the usual UK maximum is 20 mg daily, so the dose or statin choice requires prescriber review before supply. Supply simvastatin 40 mg and check creatine kinase after four weeks: Prospective CK testing does not remove the excessive exposure or replace an immediate prescription review. Supply simvastatin 40 mg twelve hours apart from daily amlodipine: The interaction is metabolic and is not prevented by separating administration times. Reduce amlodipine to 5 mg and retain simvastatin 40 mg: Changing antihypertensive treatment without review is inappropriate and does not follow the simvastatin dose restriction. Use simvastatin 40 mg on alternate days with daily amlodipine: Both medicines are intended for daily use; intermittent omission is unsafe and does not manage the interaction reliably.
Reference: BNF: simvastatin: https://bnf.nice.org.uk/drugs/simvastatin/; BNF: amlodipine: https://bnf.nice.org.uk/drugs/amlodipine/