Miconazole Warfarin Interaction — ORE Part 1 MCQ

Correct answer: B — It increases anticoagulation, raising INR and bleeding risk

**Answer: A.** Miconazole inhibits cytochrome P450 enzymes including CYP2C9, thereby potentiating warfarin. The clinically important consequence is excessive anticoagulation, with raised INR and bleeding risk; this can occur with oral gel because it is systemically absorbed. UK MHRA advice is to use caution where concomitant treatment is planned and to ensure anticoagulant monitoring and titration. **B** and **E** describe the opposite pharmacological effect. **C** is unsafe because this is a well-recognised, clinically significant interaction. **D** is incorrect: the key established interaction in this scenario is with warfarin, not only direct oral anticoagulants. In practice, the dentist should liaise with the prescriber/anticoagulation service rather than initiate miconazole without consideration of this interaction.

Reference: Medicines and Healthcare products Regulatory Agency, Drug Safety Update: "Miconazole (Daktarin): over-the-counter oral gel contraindicated in patients taking warfarin", 26 September 2017. https://www.gov.uk/drug-safety-update/miconazole-daktarin-over-the-counter-oral-gel-contraindicated-in-patients-taking-warfarin