Heparin


Heparin
An anticoagulant (anti-clotting) medication. Heparin is useful in preventing thromboembolic complications (clots that travel from their site of origin through the blood stream to clog up another vessel). Heparin is also used in the early treatment of blood clots in the lungs (pulmonary embolisms).
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An anticoagulant principle that is a component of various tissues (especially liver and lung) and mast cells in humans and several mammalian species; its principal and active constituent is a glycosaminoglycan composed of d-glucuronic acid and d-glucosamine, both sulfated, in 1,4-α linkage, of molecular weight 6,000–20,000. In conjunction with a serum protein cofactor (the so-called h. cofactor), h. acts as an antithrombin and an antiprothrombin. Synthetic preparations are commonly used in therapeutic anticoagulation. It also enhances activity of “clearing factors” (lipoprotein lipases). SYN: heparinic acid.
- h. eliminase SYN: h. lyase.
- h. lyase an enzyme eliminating Δ-4,5-d-glucuronate residues from h. and similar 1,4-linked polyglucuronates. SYN: h. eliminase, heparinase.
- h. sodium a mixture of active principles (usually obtained from various tissues of domestic animals) having the properties of prolonging the clotting time of human blood.

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hep·a·rin 'hep-ə-rən n a glycosaminoglycan sulfuric acid ester that occurs esp. in the liver and lungs, that prolongs the clotting time of blood by preventing the formation of fibrin, and that is administered parenterally in the form of its sodium salt in vascular surgery and in the treatment of postoperative thrombosis and embolism see LIQUAEMIN compare ANTIPROTHROMBIN, ANTITHROMBIN

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n.
an anticoagulant produced in liver cells, some white blood cells, and certain other sites, which acts by inhibiting the action of the enzyme thrombin in the final stage of blood coagulation. An extracted purified form of heparin is widely used for the prevention of blood coagulation both in patients with thrombosis and similar conditions and in blood collected for examination. The drug is usually administered by injection and the most important side-effect is bleeding. See also low-molecular-weight heparin.

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hep·a·rin (hepґə-rin) [Gr. hēpar liver] a sulfated glycosaminoglycan of mixed polysaccharide nature varying in molecular weights and composed of polymers of alternating derivatives of D-glycosamine and L-iduronic acid or D-glucuronic acid; it is released by mast cells and by basophils of the blood and is present in many tissues, especially the liver and lungs. Heparin is a mixture of active principles, some of which have potent anticoagulant properties that result from binding to and greatly enhancing the activity of antithrombin III and from inhibition of a number of coagulation factors, particularly activated factor X (factor Xa). Heparin also has lipotrophic properties, promoting transfer of fat from the blood to the fat depots by activation of lipoprotein lipase.

Medical dictionary. 2011.