Possible potentiation of warfarin by fluconazole

Fluconazole, a new triazole antifungal agent, interacts with a number of drugs. Only one study to date has examined the potentiation of warfarin's anticoagulant effect by fluconazole. To our knowledge, this is the first published case report of this interaction in the clinical setting. The patient had received a stable dosage regimen of warfarin for a number of months. Fluconazole 100 mg bid was added for a candidal wound infection. The prothrombin time increased from 19 to 65 seconds eight days later and the patient experienced a gastrointestinal bleeding episode. Fresh-frozen plasma was administered and warfarin was discontinued while the patient completed a planned 21-day course of fluconazole. The patient eventually resumed the original warfarin dosage with stable coagulation parameters. Until the influence of fluconazole on the anticoagulant effect of warfarin is studied in further detail, careful monitoring of coagulation parameters is recommended for all patients receiving the combination.

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				V. V. Mootha, M. L. Schluter, and A. Das Intraocular Hemorrhages Due to Warfarin Fluconazole Drug Interaction in a Patient With Presumed Candida Endophthalmitis Arch Ophthalmol, January 1, 2002; 120(1): 94 - 95. [Full Text] [PDF]