Low-molecular-weight heparins (LMWHs) represent an important therapeutic advance in the treatment of patients with venous thromboembolism. The use of LMWH has potential advantages in comparison with the use of standard unfractionated heparin (UH), including decreased binding to nonanticoagulant- related plasma proteins, greater bioavailability, longer half-life, and lower incidence of the heparin-induced thrombocytopenia syndrome. Because of the predictable anticoagulant response of LMWH when administered subcutaneously, laboratory monitoring is unnecessary, and the drug can be used to treat selected patients with venous thromboembolism in the outpatient setting. Numerous studies have shown that the treatment of venous thromboembolism with LMWH is as safe and effective as that with standard UH when both are used appropriately. Allied health personnel can easily teach most patients to self-administer LMWH subcutaneously for home use. Transition of the treatment regimen to oral warfarin anticoagulation necessitates an overlap with heparin (UH or LMWH) for at least 4 to 5 days, and the international normalized ratio should ideally be 2.0 or higher for 2 consecutive days before heparin therapy is discontinued. A practical understanding of the pharmacology, risks, and benefits of LMWH in the treatment of venous thromboembolism will enhance the primary-care physician's ability to care for patients safely and cost- effectively.
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