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H. pylori eradication interaction — GPhC CRA MCQ

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ModerateGastrointestinal TherapeuticsH. pylori eradication interactionGPhC CRA

A patient on warfarin is prescribed lansoprazole, amoxicillin and clarithromycin for H. pylori eradication. Their INR has been stable. What is the most important interaction to flag?

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Correct answer: B — Clarithromycin may increase anticoagulant effect and INR monitoring is needed

Macrolide antibiotics, including clarithromycin, can increase bleeding risk in patients taking warfarin and may affect INR. The anticoagulation service or prescriber should be informed so monitoring and dose adjustment can be arranged. This does not mean eradication therapy is impossible, but it needs risk management. Aspirin would further increase bleeding risk.

Reference: BNF