Diarrhea-associated over-anticoagulation in a patient taking warfarin: therapeutic role of cholestyramine.

We present a case of significant over-anticoagulation temporally associated with a bout of protracted diarrhea in a patient on warfarin therapy. Cholestyramine was utilized to interrupt the enterohepatic recycling of warfarin and for its antidiarrheal effects to prevent gastrointestinal vitamin K wasting. Cholestyramine enabled the use of very low doses of sc vitamin K1 (2 mg total) with subsequent attainment of a therapeutic International Normalized Ratio in 39 h.