Ulinastatin, also known as urinary trypsin inhibitor, is a kind of glycoprotein from human body, which is involved in the regulation of inflammatory response in blood. It is a kind of innate immune-related substance, which can inhibit the excessive activation of white blood cells, protect vascular endothelium and basement membrane, and inhibit the increase of vascular permeability. It is clinically used as a therapeutic drug for acute inflammation.

　　The total content of ulinastatin in the blood is very rich, which mainly exists in the former body form. The inactive precursor has a high molecular weight and weak affinity with proteolytic enzymes. It is not easy to be filtered out into the urine by the kidney, which is the way for the body to store ulinastatin. Free ulinastatin has inhibitory activity on proteolytic enzymes released in various inflammatory reactions, accounting for 2%~10% of the total content.

　　Pharmacological action of ulinastatin：

　　1. Inhibitory effect of enzyme can effectively inhibit the activities of trypsin, A-chymotrypsin, granulocyte elastase and cathepsin, and remove the damage of hydrolase in blood to tissue cells;

　　2. Anti-inflammatory effects inhibit the release of inflammatory cytokines and lysosomal enzymes, stabilize cell membranes of monocytes and neutrophils, and reduce the release of inflammatory mediators;

　　3. Improving microcirculation and tissue perfusion inhibits the generation of myocardial inhibitory factors, reduces the generation of kinidin, stabilizes lysosomal membrane, and improves metabolic abnormalities.