anticoagulant(redirected from anticoagulative)
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anticoagulant (ănˌtēkōăgˈyələnt), any of several substances that inhibit blood clot formation (see blood clotting). Some anticoagulants, such as the coumarin derivatives bishydroxycoumarin (Dicumarol) and warfarin (Coumadin) inhibit synthesis of prothrombin, a clot-forming substance, and other clotting factors. The coumarin derivatives compete with vitamin K, which is a necessary substance in prothrombin formation (see vitamin). They are only effective after the body's existing supply of prothrombin is depleted. Another anticoagulant, heparin, is a polysaccharide (see carbohydrate) found naturally in many cells. It acts in several ways: by preventing prothrombin formation; by preventing formation of fibrin, another clotting substance; and by decreasing the availability of a third clotting factor, thrombin. Heparin is obtained by extracting it from animal tissues. Anticoagulants are used to treat blood clots, which appear especially frequently in veins of the legs and pelvis in bedridden patients. Therapy helps to reduce the risk of clots reaching the lung, heart, or other organs. Heparin causes an instantaneous increase in blood-clotting time, and its effect lasts several hours.
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An agent, such as sodium citrate, that prevents coagulation of a colloid, especially blood.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. acting to prevent or impair coagulation, esp of blood
2. an agent, such as warfarin, that prevents or impairs coagulation
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005