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Clarithromycin and simvastatin — GPhC CRA MCQ

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ModerateDrug InteractionsClarithromycin and simvastatinGPhC CRA

A 52-year-old woman is prescribed clarithromycin for community-acquired pneumonia. Her repeat medication includes simvastatin 40mg at night and amlodipine 5mg daily. What is the most important interaction to flag?

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Correct answer: C — Clarithromycin can increase simvastatin exposure and myopathy risk.

Clarithromycin strongly inhibits CYP3A4 and can markedly increase simvastatin concentrations, increasing myopathy and rhabdomyolysis risk. The prescriber should be contacted to withhold simvastatin or choose an alternative antibiotic where appropriate. Amlodipine interactions may also matter, but simvastatin is the key high-risk issue here.

Reference: BNF