Heparin sodium API intermediates are the main components of heparin obtained after simple purification of crude heparin and inactivation of bacteria and viruses. They are not high purity and can not be directly processed into standard heparin preparations. By further separating and purifying crude heparin, removing nucleic acid, protein and other glycosaminoglycans and other impurities, and by eliminating heat source, inactivating virus and bacteria, controlling molecular weight and activity, refined heparin API can be obtained. It refers to API that meets pharmacopoeia quality standards and can be directly filled and processed into standard heparin preparations.

　　The refined Heparin sodium API has higher technical content than Heparin sodium API intermediates, and the production process is more complicated. Heparin directly extracted and prepared is standard heparin, also known as ordinary heparin or ungraded heparin, with a molecular weight of 5,000 to 30,000. In the late 1990s, it was found that heparin derivatives with molecular weight of 3,500 to 6,500 can be obtained by chemical or enzymatic depolymerization of ordinary heparin, which is called low molecular weight heparin.

　　A large number of clinical studies have proved that low molecular weight heparin is not easy to be neutralized by factor IV, and has stronger anticoagulation effect and fibrinolytic effect, so it has a wider range of medical uses. It has become the first choice for the treatment of acute venous thrombosis and acute coronary syndrome (angina pectoris, myocardial infarction) and other diseases. Approximately one third of the world's heparin apis are used to make standard heparin preparations, and the remaining two-thirds are used as raw materials to produce low molecular weight heparin apis.