Enoxaparin: an update of its clinical use in the management of acute coronary syndromes

Abstract

Enoxaparin (enoxaparin sodium) is a low molecular weight heparin (LMWH) indicated for use in the treatment of ischaemic complications of unstable angina and non-Q wave myocardial infarction (MI). Unfractionated heparin (UFH) has for many years represented the standard in anticoagulant therapy for patients with acute coronary syndromes; however, recent studies suggest that enoxaparin is also a viable option for anticoagulant therapy in these patients. The ESSENCE (Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q wave Coronary Events) and the TIMI 11B (Thrombolysis in Myocardial Infarction) studies reported that twice daily enoxaparin was significantly more effective than a continuous infusion of UFH in reducing the composite triple endpoint of death, MI, or recurrent angina or urgent revascularisation. Follow-up of both patient populations showed continued benefit associated with enoxaparin. Enoxaparin has been compared with tinzaparin in the treatment of unstable coronary artery disease using a nonblind study design. There was no difference between treatment groups in the therapeutic endpoints. Three nonblind studies have also compared the effects of enoxaparin and UFH in patients receiving thrombolytic therapy following acute MI. The HART II (Heparin and Aspirin Reperfusion Therapy), the ASSENT 3 (Assessment of the Safety and Efficacy of a New Thrombolytic Regimen) and the ENTIRE-TIMI 23 (Enoxaparin and Tenecteplase with or without glycoprotein IIb/IIIa Inhibitor as Reperfusion strategy in ST Elevation MI - Thrombolysis in Myocardial Infarction) studies have revealed that enoxaparin in combination with alteplase or tenecteplase is at least equivalent (HART II and ENTIRE-TIMI 23), and possibly superior (ASSENT 3) to UFH. Enoxaparin is administered as a twice-daily subcutaneous injection. In contrast, UFH is administered as an intravenous infusion which requires routine monitoring of the activated partial thromboplastin time to ensure adequate levels of anticoagulation are maintained. During the acute phase of the the ESSENCE and TIMI 11B studies, the incidence of major bleeding was similar in patients receiving enoxaparin to that in patients receiving UFH. In contrast, the rates of minor bleeding were higher in patients receiving enoxaparin than in those receiving UFH throughout these studies.

Conclusions: Data from the ESSENCE, TIMI 11B and ASSENT 3 studies have prompted calls for those LMWHs which have been shown to be superior to UFH, to be considered as first choice treatment for anticoagulation in unstable coronary syndromes. To date, these suggestions are not reflected in current guidelines which consider UFH and LMWHs equally. Irrespective, the clinical data reported in this review support the use of enoxaparin in the treatment of acute coronary syndromes. These data suggest that enoxaparin shows certain clinical and practical advantages over standard treatment with UFH and represents an important development in the treatment of acute coronary syndromes.