An oral anticoagulant. It's indications include CVA, MI, DVT, and pulmonary embolism in surgery patients. Also used to prevent thromboembolic events in high risk patients (following MI, or a-fib). Unlike heparin, this anticoagulant can take several days to reach it's max effect. This explains why the use of this and heparin are overlapped. This drug inhibits the action of vitamin K, and synthesis of clotting factors II, VII, and X are diminished. Because these clotting factors are normally circulating in the blood, it takes several days for their plasma levels to fall and for this drug to take effect. Another reason for the slow onset is that 99% of the drug is bound to plasma proteins and is thus unavailable to produce it's effect. For overdose, treat with Vit. K.Pharm class: Vit. K antagonist.