A patient on warfarin for atrial fibrillation (INR 2.8) is started on fluconazole for oral candidiasis. After 5 days, INR rises to 7.2 with minor gingival bleeding. The most appropriate management is:
- A Hold warfarin, give oral vitamin K 2.5–5 mg, recheck INR in 24 hours ✓
- B Immediately administer fresh frozen plasma and prothrombin complex concentrate
- C Continue warfarin at the same dose and monitor INR in one week
- D Switch to heparin infusion until INR falls below 3
Correct answer: A. Hold warfarin, give oral vitamin K 2.5–5 mg, recheck INR in 24 hours
Explanation
Fluconazole is a potent CYP2C9 inhibitor; CYP2C9 is the primary enzyme metabolising the more potent S-warfarin enantiomer. Inhibition raises warfarin plasma levels, dramatically elevating INR. For INR 5–9 with minor or no bleeding, guidelines recommend withholding warfarin and giving low-dose oral vitamin K (2.5–5 mg). FFP/PCC is reserved for INR > 10 with serious bleeding or emergencies.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.