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Fondaparinux / Arixtra

- See Lovenox

- Discussion:
    - synthetically manufactured pentasaccharide anticoagulant;
    - inhibitor of antithrombin (see coagulation cascade);
    - in contrast to heparins (which inactivate factor Xa and thrombin), fondaparinux only inhibits antithrombin;
    - dosage: 2.5 mg SQ q24

Effect of low molecular weight heparin (dalteparin) and fondaparinux (Arixtra) on human osteoblasts in vitro.

Efficacy of fondaparinux for thromboprophylaxis in hip fracture patients.

- Pentasaccharides:
    - in the report by Turpie, et al., the authors studied the effects of the pentasaccharide Org31540/SR90107A,
           a highly selective, indirect inhibitor of activated factor X, is the first of a new class of synthetic antithrombotic agents;
           - in a double-blind study, patients were randomly assigned to postoperative administration of one of five daily
                  doses of Org31540/SR90107A, given once daily, or to 30 mg of enoxaparin, given every 12 hours;
           - treatment was continued for 10 days or until bilateral venography was performed after a minimum of 5 days;
           - of 933 patients treated, 593 were eligible for the efficacy analysis;
           - with Org31540/SR90107A a dose effect was observed (P=0.002), with rates of venous thromboembolism of 11.8 %,
                  6.7 %, 1.7 %, 4.4 %, and 0 % for the groups assigned to 0.75 mg, 1.5 mg, 3.0 mg, 6.0 mg, and 8.0 mg of
                  the drug, respectively, as compared with a rate of 9.4 % in the enoxaparin group;
           - reduction in the risk of venous thromboembolism was 82 percent for the 3.0-mg Org31540/SR90107A group (P=0.01) and
                  29 percent for the 1.5-mg group (P=0.51);
           - enrollment in the 6.0-mg and 8.0-mg Org31540/SR90107A groups was discontinued because of bleeding complications;
           - major bleeding occurred 3.5 percent less frequently in the 0.75-mg group (P=0.01) and 3.0 percent less frequently
                  in the 1.5-mg group (P=0.05) than in the enoxaparin group (in which the rate was similar to that in the 3.0-mg group);
           - authors concluded that Org31540/SR90107A, a synthetic pentasaccharide, has the potential to improve significantly the risk-benefit
                  ratio for the prevention of venous thromboembolism, as compared with low-molecular-weight heparin.
           - references:
                  - A Synthetic Pentasaccharide for the Prevention of Deep-Vein Thrombosis after Total Hip Replacement 
                             Turpie AG, et al. New Engl J Med. 2001;344(9):619-625.