ABSTRACT
The low-molecular-weight heparins (LMWHs) were initially developed and evaluated as
antithrombotic agents for the prevention of venous thromboembolism (VTE). More than 25
years later, these drugs are still the most extensively studied class of anticoagulants [1-3].
Demonstration of the efficacy of the LMWHs has transformed the prevention and treatment of
thromboembolic disorders. There is now substantial evidence that LMWHs are as effective as
unfractionated heparin (UFH) in the prevention of VTE in moderate-risk surgical and medical
patients, and is more effective than heparin or warfarin in high-risk surgical groups, including
major orthopedic surgery and multiple trauma patients. The most dramatic clinical impact of
LMWHs has been on the initial treatment of VTE. Numerous clinical trials and subsequent
metanalyses have clearly demonstrated that LMWHs are an effective and safe alternative to UFH
for treatment of deep-vein thrombosis. Further clinical trials have demonstrated the feasibility
and safety of LMWHs for the outpatient management of VTE, and several cost-effectiveness
analyses have indicated the potential for substantial financial savings for the health care system.
These findings have revolutionized the initial management of VTE. In many countries, outpatient
LMWH is now the treatment of choice for most patients with acute VTE. Recent clinical trials
have explored the use of LMWHs for the long-term treatment of VTE as an alternative to oral
anticoagulants.
