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Warfarin and miconazole — GPhC CRA MCQ

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EasyDrug InteractionsWarfarin and miconazoleGPhC CRA

A patient taking warfarin with a target INR of 2.5 asks to buy miconazole oral gel for a sore mouth. Their INR was 3.1 yesterday. What is the most important interaction to flag?

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Correct answer: D — Miconazole can markedly increase INR and bleeding risk

Miconazole oral gel can strongly inhibit warfarin metabolism and increase anticoagulant effect. The recent INR of 3.1 makes the bleeding risk more concerning. The patient should be referred for an alternative and anticoagulation advice. This interaction is a classic high-risk pharmacy scenario.

Reference: BNF