Low-molecular-weight heparins in the management of unstable angina

Low-molecular-weight heparins (LMWHs) are derivatives of unfractionated heparin (UFH) and have a more favourable pharmacokinetic profile and a more predictable anticoagulant effect than UFH. These features allow the subcutaneous injection of weight-adjusted doses of LMWHs without monitoring of blood coagulation, and this results in cost savings. Clinical trials have shown that combined therapy with aspirin and LMWHs is significantly more effective than aspirin alone in reducing the risk of cardiac events in the acute treatment of patients affected by unstable angina. LMWHs have also been shown to be at least as safe and effective as UFH in reducing the incidence of death and myocardial infarction in patients with unstable angina. LMWHs appear to be at least as safe as UFH with regard to major bleeding risk. When given as extended therapy, LMWHs have been shown to be superior to placebo at 30 and 45 days, with an acceptable risk of bleeding. Additionally, LMWHs can be used as a 'bridge' to revascularization in patients for whom early invasive treatment is not readily available.