Fondaparinux sodium: A selective inhibitor of factor Xa

The pharmacology and mechanism of action of fondaparinux sodium are describ ed. Fondaparinux sodium is the first agent of a new class of anticoagulants tha t selectively target factor Xa. It has a linear, dose-dependent pharmacokin etic profile, which provides a highly predictable response. It is 100% bioa vailable, has a rapid onset of action, and has a half-life of 14 to 16 hour s, allowing for sustained antithrombotic activity over a 24-hour period. Th e drug does not affect prothrombin time or activated partial thromboplastin time, nor does it affect platelet function or aggregation. Studies in pati ents with confirmed heparin-induced thrombocytopenia demonstrate that the d rug is not associated with in vitro cross-reactivity to heparin antibodies. Fondaparinux sodium appears to meet the criteria for an ideal antithromboti c agent: equal or better effectiveness than currently available agents, a l ow bleeding risk, no need for laboratory monitoring, and once-daily adminis tration.