[Subarachnoid hemorrhage following commencement of danazol treatment in a patient well controlled on warfarin anticoagulation]

A 45-year-old woman with prosthetic valves replacement, was admitted with severe headache and vomiting one month after starting danazol treatment at 300 mg per day. She was receiving long-term anticoagulation with warfarin and dipyridamole, taking 3.5 mg and 300 mg per day respectively. The patient's thrombotest value was less than 6% at the time of admission. Cranial CT revealed subarachnoid hemorrhage. Warfarin and danazol treatment ware discontinued with replenishment of vitamin K. Recovery was uneventful. Danazol is 2, 3 isoxazol derivative of 17-alpha-ethinyl testosterone. As such, it shares the property of C 17 alkylated steroids in potentiating the action of coumarin. It is suggested that danazol affects the turnover of vitamin-K-dependent clotting factors, an impairment of synthesis being a likely mechanism. The possible hazard of the potentiating effect of danazol on warfarin should be widely appreciated.