Enoxaparin: the low-molecular-weight heparin for prevention of postoperative thromboembolic complications

Abstract

Objective: To introduce readers to a new low-molecular-weight heparin (LMWH) product, enoxaparin. The chemistry, pharmacology, pharmacodynamics, clinical efficacy in thromboembolic prophylaxis following surgery, and adverse effects are reviewed.

Data sources: A MEDLINE search of the English-language literature was used to identify relevant literature.

Study selection: A focus was placed on human clinical studies with well-accepted measures of antithrombotic efficacy endpoints, i.e., venography and ultrasonography. Emphasis was on pharmacologic and pharmacokinetic studies conducted in humans.

Data extraction: Most data were extracted from double-blind, controlled clinical studies. Other study designs were accepted if the results were believed to be significant. Pharmacology and pharmacokinetic data were selected from studies with exceptional design conducted in humans.

Data synthesis: Enoxaparin is a polysaccharide chain produced by the depolymerization of heparin. In comparison with heparin, which has an average molecular weight of 12,000-15,000 daltons, the average molecular weight of enoxaparin is approximately 4500 daltons. Enoxaparin does not form a complex with antithrombin III and thrombin as extensively as does heparin; however, the anti-Xa activity of enoxaparin is similar. The significance of this fact is an enhancement of antithrombotic activity and clinical efficacy. Trials comparing enoxaparin with other thromboembolic prophylaxis techniques are ongoing.

Conclusions: Thromboembolism remains one of the major complications of all surgical procedures. Attempts have been made throughout the last century to develop the most effective means to prevent this complication. Clinical studies performed throughout the world have shown that enoxaparin is superior or equivalent to other antithrombotic agents, including heparin, in preventing the formation of venous thromboembolism. In addition, enoxaparin appears to possess an equivalent or lower incidence of bleeding complications when compared with heparin prophylaxis. Enoxaparin is expected to be joined by other LMWH products in the future. As a result, the methods of providing effective prophylaxis against thromboembolic complications is expected to change in the coming years.