Detrimental effects of divalproex on warfarin therapy following mechanical valve replacement.

Drug interaction between Warfarin and psychiatric agents may have important therapeutic effects for patients undergoing cardiac surgery. We present a case of a patient in whom concurrent treatment with Warfarin and valproic acid resulted in supratherapeutic international normalized ratio values. A discussion of the possible mechanisms for this interaction as well as a review of interactions between Warfarin and other psychiatric medications is the subject of this case report.