Anticoagulants

The first effective anticoagulant agent was discovered in 1916 by a medical student, who isolated a specific coagulation inhibitor from the liver of a dog. This substance, known as heparin because it is found in high concentrations in the liver, could not be widely produced until 1933, when Canadian scientists began extracting the substance from the lungs of cattle. In 1937, researchers began using heparin to treat and prevent surgical thrombosis and embolism.

Heparin is a complex organic acid found in all mammalian tissues that contain mast cells (allergic reaction mediators). It plays a direct role in all phases of blood coagulation. In animals and humans, it is produced by mast cells or heparinocytes, which are found in the connective tissues of the capillaries, inside blood vessels, and in the spleen, kidneys, and lymph nodes. There are several types of heparin in widescale clinical use, all of which differ in physiologic activity. Various salts of heparin have been created, including sodium, barium, benzidine, and others. The most widely used form in medical practice is heparin sulfate.