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Levothyroxine and calcium — GPhC CRA MCQ

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HardEndocrine TherapeuticsLevothyroxine and calciumGPhC CRA

A patient stable on warfarin starts metronidazole today. The dentist says no anticoagulation action is needed because the antibiotic course lasts only five days. What is the best pharmacy plan?

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Correct answer: D — Notify the anticoagulation service and check INR three to five days after starting

SPS recommends an INR check three to five days after starting a medicine that may interact with warfarin, even when the course is short. The anticoagulation team can then individualise dose adjustment and follow-up according to INR, infection and bleeding risk. Dose separation does not prevent a metabolic interaction, and unplanned warfarin cessation, delayed testing or aspirin substitution can expose the patient to thrombosis or bleeding.

Reference: SPS: warfarin monitoring. https://sps.nhs.uk/monitorings/warfarin-monitoring/