Enoxaparin. A review of its clinical potential in the management of coronary artery disease.

UNLABELLED

Enoxaparin (enoxaparin sodium) is a low molecular weight heparin (LMWH) that is widely used in the prevention of deep venous thrombosis and pulmonary embolism in patients undergoing orthopaedic or general surgery. Its efficacy in these indications has led to study of its use in patients with coronary artery disease, particularly those with unstable angina, who have a high risk of myocardial infarction and death. A double-blind multicentre study [ESSENCE (Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q Wave Coronary Events)] showed that subcutaneous enoxaparin was more effective than intravenous unfractionated heparin (UFH) in reducing the incidence of the composite end-point of death, myocardial infarction or recurrent angina after 14 days in 3171 patients with recent-onset resting angina (i.e. unstable angina). There were no statistically significant between-group differences for the secondary end-point of death or myocardial infarction. Preliminary reports of long term follow-up data indicate that the clinical benefit of enoxaparin over UFH is maintained after 1 year. The only significant difference in tolerability between enoxaparin and UFH in ESSENCE was for minor haemorrhage (mostly injection-site ecchymosis), which was more common with the LMWH. Prospective pharmacoeconomic substudies of the ESSENCE trial suggest that total medical costs (including those for subsequent revascularisation procedures) for enoxaparin treatment are lower than those for UFH. The ESSENCE study is the first double-blind trial to show that a LMWH is more effective than UFH in patients with unstable angina. The superiority of enoxaparin was attributable mainly to its effects on recurrent angina. The level of anticoagulation achieved in the UFH group raises a number of issues which might have affected the apparent relative efficacy of enoxaparin and UFH. Preliminary data suggest that enoxaparin is at least as effective as UFH in reducing the incidence of subsequent cardiac events in patients receiving thrombolysis for acute myocardial infarction, and a randomised comparison with no additional treatment (other than aspirin) has demonstrated its efficacy in this indication. Enoxaparin has been ineffective in preventing restenosis after angioplasty

CONCLUSIONS

The ESSENCE study has shown that enoxaparin is more effective than UFH in patients with unstable angina. Although clarification of some methodological issues would be beneficial, the available efficacy data, together with the practical advantages of LMWHs in general, suggest that enoxaparin is an effective and convenient means of treating unstable angina and should provide cost savings compared with UFH.