Clinical and experimental experience with factor Xa inhibitors

Cardiovascular disease is the major cause of mortality in the industrial world today. We are constantly moving towards new and better ways of fighting this epidemic. Advances have been made in various fields such as patient education, imaging techniques, interventional cardiology, and novel therapeutic agents. In particular, antithrombotics are being studied with great interest and hope. Amid this class of agents, factor Xa inhibitors have already begun to show promising results in trials involving patients with acute coronary syndromes. Whereas DX-9065a is in late stage clinical trials, fondaparinux sodium is available for clinical use. Promising results have been obtained with fondaparinux sodium in patients with coronary artery disease in the PENTUA (Pentasaccharide in Unstable Angina) and PENTALYSE (Pentasaccharide as an Adjunct to Fibrinolysis in ST-Elevation Acute Myocardial Infarction) trials. Besides having a direct effect on the coagulation cascade, they have shown properties that indirectly influence the remodeling of plaques in the coronary circulation. Available evidence on factor Xa inhibitors does not ensure a remedy to acute coronary syndromes but it gives hope of improving current treatments and reducing the morbidity and mortality of cardiovascular disease. The efficacy and tolerability of fondaparinux sodium in the prevention and treatment of deep vein thrombosis (with or without pulmonary embolism) has been established in several large trials such as PENTATHLON (Pentasaccharide in Total Hip Replacement Surgery), PENTAMAKS (Pentasaccharide in Major Knee Surgery), EPHESUS (European Pentasaccharide Hip Elective Surgery), PENTHIFRA (Pentasaccharide in Hip-Fracture Surgery), and PENTHIFRA-Plus. Whereas fondaparinux sodium offers benefits over low molecular weight heparins and unfractionated heparin, the incidence of bleeding complications was greater with fondaparinux sodium than with unfractionated heparin. Treatment with factor VIIa can reverse the anticoagulant effect of fondaparinux sodium and this may be particularly important in patients who need to undergo emergency surgical procedures. Fondaparinux sodium has been recently approved for use, in conjunction with warfarin, in patients with symptomatic deep vein thrombosis or acute pulmonary embolism based on the results of two large trials conducted by the Matisse investigators. In conclusion, these observations strongly suggest the clinical potential of this class of agents in preventing arterial and venous thrombosis.