What is the mechanism of action of warfarin?

The mechanism of action of warfarin involves being a vitamin K antagonist. Warfarin works by interfering with the synthesis of vitamin K-dependent clotting factors in the liver. These factors include Factor II (prothrombin), Factor VII, Factor IX, and Factor X. By inhibiting the action of vitamin K, warfarin effectively reduces the production of these clotting factors, thereby prolonging the time it takes for blood to clot and reducing the risk of thromboembolic events.

In contrast, other options pertain to different classes of anticoagulants. Inhibiting platelet aggregation refers to mechanisms employed by agents like aspirin or clopidogrel, which target the platelet activation pathway rather than affecting clotting factor synthesis. Direct thrombin inhibitors, such as dabigatran, work by specifically inhibiting thrombin to prevent the conversion of fibrinogen to fibrin. Factor Xa inhibitors, like rivaroxaban or apixaban, directly inhibit Factor Xa, which plays a central role in the coagulation cascade. These medications act differently from warfarin and do not involve the vitamin K-dependent mechanism of clotting factor synthesis.