Current concepts of warfarin therapy.

Oral anticoagulants are used extensively, although their risks are not always fully recognized. The prophylaxis of venous thrombosis after hip surgery, the prevention of deep venous thrombosis and pulmonary emboli after an acute episode of these, the prevention of arterial emboli from the heart in patients at risk, and the prophylaxis of thrombosis in patients with congenital deficiency of antithrombin III, protein C, or protein S are some of the indications for oral anticoagulant use. Warfarin sodium is contraindicated in pregnancy, however. The recommended prothrombin time is 1 1/2 to two times control, lower than previously. The major risk of oral anticoagulant therapy, bleeding, is treated with vitamin K or plasma, depending on its severity. Warfarin necrosis and the "purple-toe" syndrome are seen more frequently than realized.