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Heparin, also known as unfractionated heparin (UFH), is a medication and naturally occurring glycosaminoglycan. [3] [4] Heparin is a blood anticoagulant that increases the activity of antithrombin. [5] It is used in the treatment of heart attacks and unstable angina. [3] It can be given intravenously or by injection under the skin. [3]
Low-molecular-weight heparin (LMWH) is a class of anticoagulant medications. [1] They are used in the prevention of blood clots and, in the treatment of venous thromboembolism (deep vein thrombosis and pulmonary embolism), and the treatment of myocardial infarction.
Heparin may be used for both prevention and the treatment of thrombosis. It exists in two main forms: an "unfractionated" form that can be injected under the skin (subcutaneously) or through an intravenous infusion, and a "low molecular weight" form that is generally given subcutaneously.
Heparin and warfarin are used to inhibit the formation and growth of existing thrombi, with the former used for acute anticoagulation while the latter is used for long-term anticoagulation. [8] The mechanism of action of heparin and warfarin are different as they work on different pathways of the coagulation cascade. [13]
An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. [1] Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which help keep the bite area unclotted long enough for the animal to obtain blood.
Hemostasis is maintained in the body via three mechanisms: Vascular spasm: Vasoconstriction is produced by vascular smooth muscle cells, and is the blood vessel's first response to injury. The smooth muscle cells are controlled by vascular endothelium, which releases intravascular signals to control the contracting properties.
Manipulation of prothrombin is central to the mode of action of most anticoagulants. Warfarin and related drugs inhibit vitamin K-dependent carboxylation of several coagulation factors, including prothrombin. Heparin increases the affinity of antithrombin to thrombin (as well as factor Xa).
A newer model of coagulation mechanism explains the intricate combination of cellular and biochemical events that occur during the coagulation process in vivo. Along with the procoagulant and anticoagulant plasma proteins, normal physiologic coagulation requires the presence of two cell types for formation of coagulation complexes: cells that ...