A warfarin-piroxicam drug interaction

A piroxicam-warfarin interaction is presented with a discussion of the possible mechanism of action. A 60-year-old white male on warfarin therapy for recurrent pulmonary embolism and deep venous thrombophlebitis showed a decrease in his previously therapeutic and stable prothrombin time when piroxicam was discontinued from his drug regimen. On two rechallenges over a ten-month period, his prothrombin times showed consistent and clinically significant fluctuations as piroxicam was added and deleted from his drug regimen.