Coagulation factor IXa and coagulation factor VIIa (Factor IXa and Factor VIIa)

Coagulation factor IXa and coagulation factor VIIa are activated forms of two vitamin K–dependent serine protease enzymes crucial for hemostatic blood clot formation. Factor VIIa, in complex with tissue factor, initiates the extrinsic pathway, activating Factor IX and Factor X, which then propagate the coagulation cascade. Factor IXa, with its cofactor Factor VIIIa, forms the intrinsic tenase complex, which greatly amplifies the generation of Factor Xa and thus thrombin, crucial for fibrin clot formation. Recombinant forms of Factor VIIa are directly administered to treat hemophilia patients with inhibitors to other factors or in cases of acute bleeding. Both factors are key therapeutic and pathophysiological targets in bleeding and clotting disorders.

Other names

Factor IX (activated)Christmas factor (for Factor IX)Factor VII (activated)Proconvertin (for Factor VII)Activated blood coagulation factor VIIrFIXa (for recombinant)rFVIIa (for recombinant)

Promoting hemostasis by activating Factor X (to Xa) and Factor IX (to IXa) (VIIa function, with tissue factor); Amplifying thrombin generation via formation of tenase (Factor IXa:VIIIa complex on platelet surface); Used therapeutically to bypass deficiencies in FVIII or FIX (as in hemophilia) by directly activating the common coagulation pathway