Heparin is a widely used anticoagulant drug in clinical practice, which can be used to prevent and treat a variety of thrombotic diseases. Heparin itself has a negative charge, can interfere with multiple links in the clotting process, and has an anticoagulant effect in vitro and in vivo.

　　The anticoagulant mechanism of heparin is mainly two aspects. One is that heparin acts directly on coagulation factor X, blocking endogenous and exogenous coagulation pathways, and playing an anticoagulant role. Secondly, by combining with antithrombin III, it can enhance the inhibitory effect of the latter on the activity of coagulation factors, especially on the inhibitory effect of coagulation factor II, so as to play an anticoagulation role.