Low molecular heparin is widely used in clinical in recent years new anticlotting drugs, the drug is with plasma antithrombin Ⅲ (AT - Ⅲ) or combined heparin cofactor Ⅱ, change the AT - Ⅲ structure, forming complexes on the activity of anticoagulant factor Xa selective inhibition effect, because of its small molecular weight, the platelet factor Ⅳ inhibitory effect is small, Therefore, it has the advantages of strong antithrombotic effect, high bioavailability, long half-life and no need for monitoring. After subcutaneous injection of LMWH, the effect was effective 30-60min, and reached the peak at 2h, lasting about 12h. It is mainly used in clinical anticoagulant treatment of acute coronary syndrome.

　　Compared with ordinary heparin, low molecular weight heparin sodium has higher bioavailability, longer half-life and fewer side effects, which has been widely used in the prevention and treatment of thrombosis and related diseases. However, studies have shown that subcutaneous injection of low molecular weight heparin sodium to patients is prone to subcutaneous hemorrhage, which is also one of the most common adverse reactions, and may even lead to subcutaneous hematoma sclerosis and skin necrosis, and some patients will thus have a greater psychological burden, affecting the efficacy.