A Case of Azathioprine Induced Warfarin Resistance in Behcet's Disease

ABSTRACT

Behcet's disease is characterized by recurrent oral aphthous ulcers, genital ulcers, uveitis, and skin lesions. Thrombosis associated with vascular inflammation in patients with Behcet's disease presents various clinical symptoms. Warfarin is usually administered for treatment of thrombosis. However, warfarin can interact with many medications that cause various problems. A 43-year-old woman with Behcet's disease presented with a swollen right leg. Deep vein thrombosis (DVT) was confirmed, and treated with warfarin. Due to exacerbation of Behcet's disease, she received azathioprine along with warfarin. Subsequently, the international normalized ratio (INR) decreased and DVT was exacerbated. Despite an increase in the warfarin dose, the patient did not reach the target INR. After discontinuation of azathioprine, DVT improved and the warfarin dose was decreased. There were no specific findings associated with a hypercoagulable status. This finding suggests the interaction of azathioprine and warfarin. Therefore, clinicians should be cautious regarding the possibility of drug interactions between azathioprine and warfarin.