Warfarin is an anticoagulant drug normally used to prevent blood clot formation as well as migration. Indicated for: prophylaxis and treatment of venous thromboembolism and related pulmonary embolism, prophylaxis and treatment of thromboembolism associated with atrial fibrillation, prophylaxis and treatment of thromboembolism associated with cardiac valve replacement, use as adjunct therapy to reduce mortality, recurrent myocardial infarction, and thromboembolic events post myocardial infarction. Off-label uses include secondary prevention of stroke and transient ischemic attacks in patients with rheumatic mitral valve disease but without atrial fibrillation. Warfarin does not actually affect blood viscosity, rather, it inhibits vitamin-k dependent synthesis of biologically active forms of various clotting factors in addition to several regulatory factors. Warfarin is a [vitamin K] antagonist which acts to inhibit the production of vitamin K by inhibiting vitamin K epoxide reductase. By doing this the carboxylation of vitamin-k dependent factors such as II, VII, IX and X are prevented. As the concentration of reduced form of vitamin K decreases this leads to a depletion of the cofactor for future reactions that are vitamin k dependent. This ultimately leads to interference with coagulation, because of this patient should not give blood during the time they are using Warfarin. Warfarin has several properties that should be noted when used medicinally, including its ability to cross the placental barrier during pregnancy which can result in fetal bleeding, spontaneous abortion, preterm birth, stillbirth, and neonatal death. Additional adverse effects such as necrosis, purple toe syndrome, osteoporosis, valve and artery calcification, and drug interactions have also been documented with warfarin use.

Warfarin Pathway (New) References