What is the primary mechanism of action of rivaroxaban?

Rivaroxaban primarily functions as an anticoagulant by blocking the active site of factor Xa. By inhibiting factor Xa, rivaroxaban effectively disrupts the coagulation cascade, thereby preventing the conversion of prothrombin into thrombin, which is a crucial step in the generation of fibrin for clot formation. This mechanism of action allows it to reduce the risk of thromboembolic events, such as strokes in patients with atrial fibrillation or in the treatment and prevention of venous thromboembolism.

The other mechanisms mentioned are not applicable to rivaroxaban. For instance, activation of factor X would enhance clot formation rather than inhibit it, and direct inhibition of thrombin is characteristic of different anticoagulants, such as dabigatran. Lastly, rivaroxaban operates independently of antithrombin III, as it is a direct factor Xa inhibitor and does not require this substance for its anticoagulant effects. Understanding these aspects highlights the specific role rivaroxaban plays in the management of clotting disorders.