Heparin

Abstract

Heparin is a family of mucopolysaccharides found in mast cells with molecular weights from 60000 to 100000 daltons. It is composed of a linear chain of sulphated glycosaminoglycans attached to a protein core. The material used clinically is extracted from porcine intestinal mucosa or bovine lung and is dosed in units assayed against an International Standard Preparation. During isolation the core protein is removed and the polysaccharide chain degraded resulting in fragments of 5000 to 30 000 daltons. Heparin is used as an anticoagulant both in vivo and in vitro. It is immediately active by virtue of its strongly acidic nature which increases the activity of antithrombin III. Heparin is not absorbed orally but given intravenously and subcutaneously. The half-life of the drug is dose-related varying between 1 to 5 hours. Full-dose heparin therapy is monitored by measuring the activated partial thromboplastin time.