Interaction between Warfarin and Apple Juice.

For decades, warfarin has been the primary anticoagulant for the primary and secondary prevention of venous and arterial thromboembolic events. There is an extensive amount of literature that has contributed to the understanding of the complex pharmacokinetics and pharmacodynamics of warfarin, its interactions with drugs and other compounds, its antithrombotic effects, and the risks associated with its use. To the authors’ knowledge, however, there have been no case reports of an interaction between apple juice and warfarin. The following case report describes elevation of the international normalized ratio (INR) after ingestion of at least 1 L of homemade apple juice daily for 2 weeks in a patient who was previously stable on warfarin for venous thromboembolism.