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Fondaparinux is Similar to Enoxaparin in Preventing Ischemic Events Among Patients with Acute Coronary Syndromes but Causes Less Bleeding

March 22, 2006

By: Jennifer Tartaglia MS and Asher Kimchi M.D.

Ontario, Canada - Anticoagulants, antiplatelet agents, and invasive coronary procedures reduce ischemic coronary events in patients with acute coronary syndromes, but increase bleeding. Enoxaparin is a low molecular weight heparin commonly used in patients with acute coronary syndromes that reduces their risk of death or myocardial infarction (MI). A trial conducted by the Fifth Organization to Assess Strategies in Acute Ischemic Syndromes Investigators (OASIS-5) in Ontario, Canada compared the efficacy and safety of fondaparinux (Arixtra) and enoxaparin (Lovenox). The trial found that fondaparinux is similar to enoxaparin in reducing the risk of ischemic coronary events and it significantly decreases major bleeding. These results were published in the March 14, 2006 issue of The New England Journal of Medicine.

The study was randomized, double-blind, and double-dummy. It enrolled 20,078 patients with unstable angina or myocardial infarctions (MIs) without ST segment elevation. These participants were randomly assigned to receive fondaparinux 2.5mg daily and placebo enoxaparin bid or to receive enoxaparin 1mg per kg of body weight bid and placebo fondaparinux daily. Patients were followed for 90-180 days.

The primary study finding was that death, MI, or refractory ischemia at 9 days (primary outcome events) was not significantly different between fondaparinux (5.8%) and enoxaparin (5.7%; Hazard ratio (HR), 1.01; 95% confidence interval (CI), 0.90-1.13). In addition, fondaparinux was more effective at decreasing mortality after 30 days (2.9%) when compared with enoxaparin (3.5%; HR, 0.83; 95% CI, 0.71-0.97; P=0.02). Fondaparinux also substantially decreased the rate of major bleeding at 9 days (2.2%) when compared with enoxaparin (4.1%; HR, 0.52; 95% CI, 0.44-0.61; P<0.001). The investigators found the composite of death, MI, refractory ischemia, or major bleeding at 9 days in 7.3% of patients in the fondaparinux group, as compared with 9.0% of patients in the enoxaparin group (HR, 0.81; 95% CI, 0.73-0.89; P<0.001).

These findings suggest that fondaparinux, while having a similar efficacy to enoxaparin, has significantly less bleeding, which is associated with lower long-term mortality and morbidity. This increased bleeding seen with enoxaparin is thought to be due to the drug’s intrinsic properties associated with the inhibition of thrombin in combination with a current recommended dose of enoxaparin that may be too high. Consequently, the authors recommend using fondaparinux as an alternative to enoxaparin in the short-term care of patients with acute coronary syndromes.

Authors (The Writing Committee): Salim Yusuf, D.Phil., M.B., B.S., Shamir R. Mehta, M.D., Susan Chrolavicius, B.A., Rizwan Afzal, M.Sc., Janice Pogue, M.Sc., Christopher B. Granger, M.D., Andrzej Budaj, Ph.D., Ron J.G. Peters, M.D., Jean-Pierre Bassand, M.D., Lars Wallentin, Ph.D., Campbell Joyner, M.D., and Keith A.A. Fox, F.R.C.P.


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