What do Xa and IIa factors mean?

Factor Xa is a serine protease, which has the function of breaking the peptide bond in macromolecular protein, making it a small molecular protein. Factor IIa refers to coagulation factor, factor Xa and factor IIa refer to new oral anticoagulants (NOAC), among which ⅹ A and Ⅱ ⅱA _ are effective.

1. Research and development background of new oral anticoagulants: Thromboembolic diseases, such as venous thromboembolism (VTE), including deep venous thrombosis (DVT) and pulmonary embolism (PE), seriously affect the survival rate of patients. Anticoagulants are of positive significance for the prevention and treatment of this series of diseases. In the past 60 years, vitamin K antagonist VKAs, such as warfarin, as the most widely used oral anticoagulant in clinic, has played an important role in the prevention and treatment of thromboembolic diseases. Traditional anticoagulants include indirect thrombin inhibitors, such as ordinary heparin and low molecular weight heparin for factors IIa and Xa. Direct thrombin inhibitors, such as hirudin, recombinant hirudin, argatroban and cimetidine; Vitamin k antagonist warfarin, etc.

2. The classification of new oral anticoagulants:

(1) Direct thrombin inhibitor: Thrombin (coagulation factor IIA) plays a central role in the coagulation process. Direct thrombin inhibitors specifically block the activity of thrombin, thus preventing fibrinogen from splitting into fibrin and blocking the last step of coagulation cascade. The anticoagulant effect of direct thrombin inhibitor is not a cofactor and has nothing to do with vitamin K. Its anticoagulant effect is concentration-dependent, and thrombin bound to fibrin can also be inactivated. Drugs representing the Dabiga Group.

(2) Direct factor Xa inhibitor: Coagulation factor Xa is the intersection of exogenous and endogenous coagulation pathways. Prothrombin is activated by forming phospholipid complex, namely thrombin complex, on the surface of phospholipid membrane. Direct factor Xa inhibitor can prevent thrombin from being converted into thrombin by binding to the active site of factor Xa, and the anticoagulant effect is independent of endogenous anticoagulant enzyme. Representative drugs are: apixaban, rivaroxaban and iduxaban. Apixaban was superior to enoxaparin in the preliminary trial of preventing VTE in the first stage after operation, and there was no significant difference in the incidence of severe bleeding caused by the two.