Trends in the development of oral anticoagulants.

Anticoagulation remains the therapy of choice for the prevention and treatment of venous and arterial thromboembolic disorders which can cause major organ damage or death. Heparins represent the antithrombotic drugs of choice in short and medium-term prophylaxis and therapy of thromboembolic diseases. Fondaparinux, a synthetic and structural analog of the antithrombin-binding pentasaccharide domain of heparin, has selective anti-Xa activity and longer half-life. However, anticoagulants are poorly absorbed by oral route because of their high molecular weight, hydrophilicity and negative charges. Long-term anticoagulation therapy is problematic because of side effects and frequent monitoring. Formulation approaches are particularly promising.