What is the mechanism of action of heparin in anticoagulation therapy?

Heparin functions as an anticoagulant primarily by potentiating the effects of antithrombin III, which is a crucial protein in the regulation of blood coagulation. Antithrombin III serves to inhibit several enzymes in the coagulation cascade, including thrombin and factor Xa. When heparin binds to antithrombin III, it induces a conformational change that significantly increases antithrombin's affinity for these clotting factors, leading to their inactivation. This mechanism enables heparin to prevent the formation of fibrin clots, thus serving its purpose in anticoagulation therapy.

The other options do not accurately describe the primary mechanism through which heparin exerts its anticoagulation effects. While thrombin production is inhibited as a consequence of heparin's action, heparin itself does not directly inhibit thrombin production. Instead, it enhances the ability of antithrombin III to inactivate thrombin that is already present. The activation of protein C is a different anticoagulant mechanism that is independent of heparin and involves different medications. Finally, while heparin can have some effects on platelet aggregation indirectly, its main role is not to inhibit this process directly but to increase the inhibitory