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Anticoagulant and Antiplatelet Drugs - Definition, Purpose, Description,... surgeryencyclopedia.com | is antidote to newer anticoagulant drugs... emcreg.org | Update Stresses Long-Term Anticoagulant Therapy After... seconds-count.org | drugs in sport | drug use in sport pponline.co.uk |
An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some chemical compounds are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis equipment.
[edit] As medicationsAnticoagulants are given to people to stop thrombosis (blood clotting inappropriately in the blood vessels). This is useful in primary and secondary prevention of deep vein thrombosis, pulmonary embolism, myocardial infarctions and strokes in those who are predisposed. [edit] Coumarines (Vitamin K antagonists)The oral anticoagulants are a class of pharmaceuticals that act by antagonizing the effects of vitamin K. Examples include warfarin. It is important to note that it takes at least 48 to 72 hours for the anticoagulant effect to develop fully. In cases when any immediate effect is required, heparin must be given concomitantly. Generally, these anticoagulants are used to treat patients with deep-vein thrombosis (DVT), pulmonary embolism (PE), atrial fibrillation (AF), and mechanical prosthetic heart valves. [edit] Adverse effectsPatients aged 80 years or more may be especially susceptible to bleeding complications with a rate of 13 bleeds per 100 person-years.[1] These oral anticoagulants are used widely as poisons for mammalian pests, especially rodents. (For details, see rodenticide and warfarin.) Depletion of vitamin K by coumarine therapy increases risk of arterial calcification and heart valve calcification, especially if too much vitamin D is present.[2] [edit] Available agents
[edit] Heparin and derivative substancesHeparin is a biological substance, usually made from pig intestines. It works by activating antithrombin III, which blocks thrombin from clotting blood. Heparin can be used in vivo (by injection), and also in vitro to prevent blood or plasma clotting in or on medical devices. Vacutainer brand test tubes containing heparin are usually colored green. [edit] Low molecular weight heparinLow molecular weight heparin is a more highly processed product that is useful as it does not require monitoring of the APTT coagulation parameter (it has more predictable plasma levels) and has fewer side effects. [edit] Synthetic pentasaccharide inhibitors of factor Xa
[edit] Major pharmaceutical Heparin recall due to contaminationIn March 2008 major recalls of Heparin were announced by pharmaceuticals due to a suspected and unknown contamination of the raw Heparin stock imported from China [4] [5]. The U.S. Food and Drug Administration was quoted as stating that at least 19 deaths were believed linked to a raw Heparin ingredient imported from the People's Republic of China, and that they had also received 785 reports of serious injuries associated with the drug’s use. According to the New York Times: 'Problems with heparin reported to the agency include difficulty breathing, nausea, vomiting, excessive sweating and rapidly falling blood pressure that in some cases led to life-threatening shock'. [edit] Direct thrombin inhibitorsMain article: direct thrombin inhibitor Another type of anticoagulant is the direct thrombin inhibitor.[6] Current members of this class include argatroban, lepirudin, bivalirudin, and dabigatran. An oral direct thrombin inhibitor, ximelagatran (Exanta) was denied approval by the Food and Drug Administration (FDA) in September 2004 [1] and was pulled from the market entirely in February 2006 after reports of severe liver damage and heart attacks. [2] [edit] Anticoagulants outside the bodyLaboratory instruments, test tubes, blood transfusion bags, and medical and surgical equipment will get clogged up and become nonoperational if blood is allowed to clot. Chemicals can be added to stop blood clotting. Apart from heparin, most of these chemicals work by binding calcium ions, preventing the coagulation proteins from using them.
For the meaning of more colors, see Vacutainer#including coagulants. [edit] See also
[edit] References
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