Abstract
Unfractionated heparin (UFH) and Low Molecular Weight Heparins (LMWHs) represent the mainstay of agents available for the management of venous and arterial thrombosis. LMWHs represent the agents of choice for the prevention and treatment of venous thromboembolism because they have improved pharmacological and pharmacokinetic advantages. LMWHs are derived from UFH by chemical or enzymatic depolymerization; they have a mean molecular weight of 4,000 to 5,000 d. The LMWHs include dalteparin, enoxaparin, nadroparin and certoparin. They can be used inhospital or out-of-hospital because they can be administered subcutaneously without the need for laboratory monitoring and they have better bioavailability and cause less platelet activation. Several randomized trials suggested that patients with symptomatic or asymptomatic pulmonary embolism, symptomatic deep venous thrombosis can be treated with LMWH instead of UFH. Compared with UFH, LMWHs have a more predictable dose-response relationship (obviates the need for laboratory monitoring), a longer half-life (allows once-daily or twice-daily administration) and a lower risk for immune-mediated thrombocytopenia or osteoporosis. This is partly due to more targeted action: UFH acts on both thrombin and factor Xa about equally, whereas LMWHs are more active against factor Xa.
Keywords: Low-molecular weight heparins, prevention of venous thromboembolism, treatment of venous thromboembolism
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