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Amlodipine and clarithromycin — GPhC CRA MCQ

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HardDrug InteractionsAmlodipine and clarithromycinGPhC CRA

A 55-year-old woman on amlodipine 10mg daily is prescribed clarithromycin for sinusitis. She has eGFR 42mL/min/1.73m2 and previously fainted during an episode of low blood pressure. What is the most important interaction to flag?

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Correct answer: D — Clarithromycin can increase amlodipine exposure and hypotension risk

Clarithromycin can inhibit metabolism of calcium-channel blockers such as amlodipine, increasing hypotension risk. Previous fainting and renal impairment increase concern about adverse outcomes. The prescriber may choose an alternative antibiotic or advise monitoring and dose adjustment. The pharmacist should flag the interaction rather than relying on patient tolerance.

Reference: https://www.pharmacyregulation.org/registration-assessment#stage-8-order-88