Возвращаясь к старому...
Вот такие предположения стали циркулировать в периодике:
The reduction in bleeding with fondaparinux compared with enoxaparin in the OASIS-5 trial was unexpected. Both fondaparinux and enoxaparin exert their anticoagulant effect by activating AT, thereby accelerating the inhibition of factor Xa by AT. A percentage of the longer enoxaparin chains also inhibit thrombin in an AT-dependent manner, but the short pentasaccharide chain of fondaparinux does not inhibit thrombin. Indirect evidence suggests that the excessive bleeding with enoxaparin (over fondaparinux) is unlikely to be caused by its AT effect. Thus, UFH blocks thrombin more effectively than enoxaparin but does not cause more bleeding,31,32 and the direct thrombin inhibitors bivalirudin and argatroban do not cause more bleeding than UFH or LMWH.34 Randomized studies comparing fondaparinux and enoxaparin for the prevention and treatment of VTE also provide no support for the conclusion that intrinsic differences between the drugs account for differences in bleeding risk.
The more likely explanation for the reduced bleeding with fondaparinux in the OASIS-5 and -6 trials relates to differences in the intensity of the anticoagulant effect between the low dose of fondaparinux and the standard "therapeutic" dose of enoxaparin. The once-daily 2.5-mg dose of fondaparinux used in the OASIS-5 and -6 studies was the same as the dose that was used in earlier thromboprophylaxis trials. By contrast, the dose of enoxaparin in the OASIS-5 trial (1 mg/kg twice daily) was much higher than the dose used in orthopedic venous thromboprophylaxis trials (30 mg twice daily or 40 mg once daily). The results of the OASIS-5 and -6 studies raise the possibility that a lower anticoagulant intensity than was previously thought necessary is sufficient to prevent recurrent ischemic events and death but is much safer than the traditional (higher) intensities of enoxaparin and UFH that are currently used in the treatment of ACS.
Circulation. 2007 Jul 31;116(5):552-60.
Beyond unfractionated heparin and warfarin: current and future advances.
Hirsh J, O'Donnell M, Eikelboom JW.
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