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Home > Anticoagulant


 

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.

1 As medications

Anticoagulants 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.

1.1 Vitamin K antagonists

The oral anticoagulants are a class of pharmaceuticals that act by antagonizing the effects of vitamin K. It is important to note that they take at least 48 to 72 hours for the anticoagulant effect to develop fully. In cases when an immediate effect is required, heparin must be given concomitantly. Generally, these anticoagulants are used in prevention of embolization -- in deep-vein thrombosis (DVT), pulmonary embolism, and patients with atrial fibrillationAtrial fibrillation AF is an electrical rhythm disturbance of the heart affecting the atria. Abnormal electrical impulses in the atria cause the muscle to contract erratically and pump blood inefficiently. The atrial chambers are thus not able to complete and mechanical prosthetic heart valve s.

The most important oral anticoagulants are:

1.2 Direct thrombin inhibitors

The new drug class of the direct thrombin inhibitor s, that will be introduced in the near future, is expected to replace warfarin in some indications. Its main representative, ximelagatranXimelagatran Exanta , H 376/95) is an anticoagulant that has been investigated extensively but is awaiting approval by the Food and Drug Administration (FDA). Its manufacturer, AstraZeneca, is marketing it as a replacement for warfarin that does not need (ExantaŽ), has performed well in clinical trials and is being reviewed by the Food and Drug Administration.

1.3 Heparin and derivative substances

Heparin is a biological substance, usually made from swine 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 medical devices. VacutainerVacutainer is a trademark of Becton, Dickinson and company for a kind of test tube designed for venipuncture. Principles The vein is first punctured with the hypodermic needle, which is connected to a translucent plastic holder. The needle actually has as and test tubes containing heparin are usually colored green. Low 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 less side effects.

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