Are the Current Guidelines for the Acceptance of Generic Low Molecular Weight Heparins Adequate?

Generic Versus Branded Enoxaparin in the Prevention of Venous Thromboembolism Following Major Abdominal Surgery

Introduction: Several generic low-molecular-weight heparins (LMWHs) have recently become available worldwide, including the United States. Companies have filed for regulatory approval of generic versions in many countries, based only on compound biochemical characteristics or its immunogenicity. Methods: Prospective study to evaluate the comparative effect of 2 enoxaparins (Sanofi-Aventis branded enoxaparin [SAe] vs eurofarma-enoxaparin [Ee], a generic version) as prophylaxis for venous thromboembolism (VTE) following major abdominal surgery. A total of 200 patients were randomized in a 1:1 ratio either to receive 40 mg of SAe or Ee subcutaneously (sc) once daily (od) postoperatively for 7 to 10 days. Compressive ultrasound was performed on day 10 + 4. Results: No statistically significant differences between the 2 groups were detected. In all, 2 SAe patients presented deep vein thrombosis ([DVT] 2.1%), none of the Ee group. No major bleeding events occurred. Conclusions: This exploratory trial suggests that the generic LMWH is probably as safe and as effective as the branded enoxaparin (Lovenox, Brazil) in the prophylaxis of VTE in this population.

Are all low molecular weight heparins equivalent in the management of venous thromboembolism?

Low molecular weight heparins are replacing unfractionated heparin in a number of clinical indications because of their improved subcutaneous bioavailability and more predictable antithrombotic response. Clinical trials have demonstrated that low molecular weight heparins are at least as safe and effective as unfractionated heparin for the initial treatment of venous thromboembolism, and unfractionated heparin and warfarin for primary and secondary thromboprophylaxis. The mechanism behind the antithrombotic action of low molecular weight heparins is not fully understood but is likely to involve inhibition of coagulation factors Xa and IIa (thrombin), release of tissue-factor-pathway inhibitor, and inhibition of thrombin activatable fibrinolytic inhibitor. Different low molecular weight heparins have been shown to have various effects on coagulation parameters. Seven low molecular weight heparins are currently marketed worldwide, each demonstrated distinct chemical entities with unique pharmacokinetic and pharmacodynamic profiles. Each low molecular weight heparin is approved for specific indications based on the available efficacy and safety data for that product. The relative efficacy and safety of the low molecular weight heparins are unclear because there have been very few direct comparisons in randomized clinical trials. While recommending low molecular weight heparins for the prevention and treatment of venous thromboembolism, clinical guidelines have not specified individual agents. National and international organizations recognize that low molecular weight heparins are distinct entities and that they should not be used interchangeably in clinical practice. Each low molecular weight heparin should be used at the recommended dose when efficacy and safety data exist for the condition being treated. When these data are not available, the dosing and administration of low molecular weight heparins must be adapted from existing data and recommendations.