[Anti-Xa molecules]

Factor Xa plays a central role in the mechanisms of thrombin generation. Recently, molecules have been developed which either catalyse the inactivation of factor Xa by the antithrombin (pentasaccharide) or directly inhibit factor Xa (synthetic inhibitor or peptides extracted from the saliva of tics or leeches). These new molecules allowed to demonstrate that selective factor Xa inhibition exerts an antithrombotic effect in several models of thrombosis. The molecule at the most advanced stage of development is pentassaccharide (phase II), synthetic ultra low molecular weight heparin, with a well defined mechanism of action.