Heparin is a mucopolysaccharide contained in mammals, which is combined with proteins and exists in intestinal mucosa, lung, liver and other organs. After separation and extraction of heparin and protein, it has a variety of physiological activities such as anticoagulation, antithrombosis, and lowering blood lipids. It is a potent drug to prevent atherosclerosis and cardiovascular and cerebrovascular diseases.

　　1. Ordinary (standard) heparin is extracted from pig or sheep mucosa with an average molecular weight of 15000, which is quite stable.

　　2. Low molecular weight heparin is usually referred to as a molecular weight less than 6000. Compared with ordinary heparin, low molecular weight heparin has longer half-life, better antithrombotic effect, and weaker anticoagulant bleeding tendency, so it has the tendency to replace ordinary heparin. In recent years, the common clinical use of dapheparin sodium, enoxaparin sodium, low molecular weight heparin calcium.

　　3. Currently, heparin preparations with low anticoagulant activity, heparin modified configuration, heparin-like and so on are under further study. These drugs have the advantages of low anticoagulant activity, high antithrombolysis, long action time and less bleeding effect, which have great development prospects.