Heparin Health Dictionary

An anticoagulant drug used to prevent and treat abnormal blood clotting. Heparin is given by injection and is used as an immediate treatment for deep vein thrombosis or for pulmonary embolism. Newly developed “low molecular weight heparins”, for example tinzaparin, which need to be injected once a day, are now widely used and can be self-administered at home.

Adverse effects of heparin include rash, aching bones, and abnormal bleeding in different parts of the body. Long-term use may cause osteoporosis.

Heparin is one of the naturally produced ANTICOAGULANTS with a rapid e?ect, which is thought to act by neutralising thrombin (see COAGULATION). Inactive when taken orally, it is normally given intravenously – it may be given for a few days, combined with an oral anticoagulant such as warfarin, to initiate anticoagulation. Low-dose heparin may be given by subcutaneous injection for longer periods, for the prophylaxis of DEEP VEIN THROMBOSIS (DVT) or PULMONARY EMBOLISM in ‘high-risk’ patients, such as those with obesity or a history of thrombosis, or post-operatively. If haemorrhage occurs, withdrawal of heparin is usually su?cient, but protamine sulphate is a rapidly active and speci?c antidote. Prolonged treatment with heparin may cause osteoporosis (see under BONE, DISORDERS OF).

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 deep vein thrombosis and similar conditions and in blood collected for examination. The most important side-effect is bleeding. See also low-molecular-weight heparin.