Enoxaparin. A reappraisal of its pharmacology and clinical applications in the prevention and treatment of thromboembolic disease.

Enoxaparin (enoxaparin sodium) is a low molecular weight derivative of unfractionated heparin which has been evaluated for the treatment and prevention of thromboembolic disease. Since a previous review in Drugs, well controlled clinical trials have confirmed the effectiveness of enoxaparin as prophylaxis in patients with a high risk for deep venous thrombosis (DVT), i.e. those undergoing hip or knee replacement surgery. Enoxaparin 30mg twice daily, initiated postoperatively, offers an overall balance of prophylactic efficacy and haemorrhagic tolerability which is superior to that of unfractionated heparin. In comparative clinical trials, this dosage demonstrated either improved efficacy and a similar haemorrhagic profile, or a similar degree of efficacy with a lower rate of haemorrhagic events, compared with unfractionated heparin 5000IU 3 times daily. Limited data indicate that an enoxaparin regimen of 40mg once daily, starting preoperatively, is more effective than unfractionated heparin in patients undergoing hip replacement and has a comparable haemorrhagic profile. In patients with a moderate risk for DVT, enoxaparin is similar to unfractionated heparin in both efficacy and haemorrhagic profile, while preliminary investigations have demonstrated the utility of enoxaparin in the prevention of DVT in elderly, nonsurgical patients. Enoxaparin may also be useful for the treatment of existing DVT and as an anticoagulant in haemodialysis. Thus, enoxaparin is an effective form of prophylaxis for thromboembolic disease in moderate to high risk surgical situations. Recent evidence for improved efficacy, together with a similar incidence of haemorrhagic complications in most situations, may lead to enoxaparin being preferred to unfractionated heparin for the routine prevention of DVT after high risk surgery. Although detailed comparisons with other low molecular weight heparins and antithrombotic agents are required before its relative clinical utility can be fully assessed, enoxaparin is likely to play a significant role in the prophylaxis of thromboembolic disorders.