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Warfarin and amiodarone — GPhC CRA MCQ

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ModerateDrug InteractionsWarfarin and amiodaroneGPhC CRA

A patient stabilised on warfarin is prescribed amiodarone for atrial fibrillation. The anticoagulation clinic has not yet been informed. His last INR was 2.5. What monitoring is required?

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Correct answer: A — Closer INR monitoring and anticoagulation dose review

Amiodarone inhibits warfarin metabolism and can increase INR and bleeding risk. The effect may develop over days to weeks because of amiodarone's long half-life. The anticoagulation service should be informed so INR monitoring and dose adjustment can be arranged.

Reference: BNF