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.