Low-Molecular-Weight Heparin for the Treatment of Venous Thromboembolism

Abstract

There is ample evidence from clinical trials to justify giving certain low-molecular-weight heparins subcutaneously rather than administering continuous iv unfractionated heparin for the initial treatment of thromboembolism. Given subcutaneously, the low-molecular-weight heparins have a predictably high absorption rate and a prolonged duration of action. They can, therefore, be administered once or twice daily by injection to prevent or treat venous thrombosis. Furthermore, treatment does not require laboratory monitoring. Eliminating the need for continuous iv infusion and for laboratory monitoring should allow patients to be discharged earlier, and eventually lead to the outpatient treatment of venous thromboembolism. Studies to date indicate that low-molecular-weight heparin is more cost-effective than unfractionated heparin and the cost-effectiveness will be increased by out-of-hospital treatment. The information to date is that low-molecular-weight heparin is safer and more effective than continuous iv unfractionated heparin in the treatment of proximal venous thrombosis. The decreased mortality rate seen in two clinical trials, particularly in patients with metastatic cancer, was quite unexpected. This requires further confirmation in larger prospective randomized trials.