Low-Molecular-Weight Heparin

Heparin, the familiar anticoagulant, is a naturally occurring sulfated glycosaminoglycan that for commercial purposes is extracted from bovine and porcine lung or intestine; it was originally purified from the liver (hence its name). A highly charged anion, heparin has many biologic activities aside from retarding blood clotting, but that is its only practical clinical indication at present. Its anticoagulant action reflects its ability to accelerate the formation of a molecular complex between a protein constituent of normal plasma, antithrombin III, and serine proteases of the intrinsic coagulation system, thus blocking the enzymatic activity of the clotting factors. The term "antithrombin . . .