Apixaban is a selective inhibitor of clotting factor Xa (FXa). It does not require a cofactor (such as Anti-thrombin III) for activity. Apixaban inhibits free FXa, clot bound FXa and prothrombinase activity. Apixaban indirectly inhibits platelet aggregation induced by thrombin. By inhibiting FXa, Apixaban decreases thrombin generation.