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Clarithromycin and statin — GPhC CRA MCQ

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HardInfectionsClarithromycin and statinGPhC CRA

A 71-year-old man taking simvastatin 40mg nightly is prescribed clarithromycin for pneumonia. He has CKD stage 3 and asks whether to continue his usual tablets. What is the most important interaction to flag?

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Correct answer: B — Clarithromycin may increase simvastatin exposure and myopathy risk

Clarithromycin inhibits CYP3A4 and can markedly increase simvastatin exposure. This increases the risk of myopathy and rhabdomyolysis, particularly in older patients and those with renal impairment. The prescriber should be contacted to consider withholding simvastatin or using an alternative antibiotic. Chelation is not the relevant mechanism.

Reference: BNF