n.
Anticoagulant drug, marketed as Coumadin.
Originally developed to treat thromboembolism (see thrombosis ), it interferes with the liver's metabolism of vitamin K , leading to production of defective coagulation factors. Warfarin therapy risks uncontrollable hemorrhage , either spontaneously or from any cut or bruise; it requires frequent checks to maintain the proper level in the blood. In high concentrations, warfarin is used as a rodent poison, causing death by internal bleeding.