The clinical use of Fondaparinux: A synthetic heparin pentasaccharide.

Fondaparinux is a synthetic heparin pentasaccharide with a sequence identical to that found in anticoagulant heparin. It is a pure compound with a molecular weight of 1728Da. Fondaparinux catalyzes the conformational change of a serpin or serine protease inhibitor antithrombin III to accelerate the suicidal inactivation of factor Xa over 340-fold, which in turn inhibits thrombin generation in the coagulating signal transduction pathway. Fondaparinux does not inhibit thrombin activity, release tissue factor pathway inhibitor, or possess other properties of heparin such as anti-inflammatory, anti-viral, anti-angiogenesis, anti-neoplastic, and anti-metastatic effects though high affinity interactions with a variety of proteases, protease inhibitors, chemokines, cytokines, growth factors, and their respective receptors. Low antithrombin III levels in blood circulation also affects the efficacy of Fondaparinux. Thus, Fondaparinux represents a refined use of the anti-factor Xa property of heparin. As an anti-factor Xa drug, Fondaparinux has complete bioavailability subcutaneously, instant onset of action, a half-life of 15-20h, and a direct renal excretion without any metabolism. Fondaparinux has been shown to be superior to low molecular weight heparin in preventing deep vein thrombosis. Clinically, Fondaparinux is used for the prevention of deep vein thrombosis in patients who have had orthopedic surgery as well as for the treatment of deep vein thrombosis and pulmonary embolism with limitations of use in elderly, low weight, renal impaired patients and in those receiving spinal anesthesia. Clinical studies showed that Fondaparinux acts in prevention and treatment of venous thromboembolism and in ischemic heart disease without significant risk of bleeding.