New antithrobotic agents

The main clinical indications for anticoagulant agents are treatment and prophylaxis of venous and arterial thromboembolism and acute coronary syndromes. For decades, two anticoagulants, heparin and warfarin, have been the principal drugs available. Dicumaroid agents have serious limitations due to their narrow therapeutic range, needing close monitoring. The interaction with food and drugs and the numerous interindividual variations result in unstable effects on coagulation parameters. On the other side, heparins have an exclusive parenteral use and a risk of immunological adverse reactions. Heparin induced thrombocytopenia is the most serious complication. The limitations of existing oral and parenteral anticoagulant agents have prompted the search for alternative anticoagulant drugs. This paper reviews new anticoagulant agents describing their pharmacological and clinical properties. It focuses on the target of their anticoagulant action inside the coagulation pathway, and analyzes the clinical trials providing indications for new clinical anticoagulation strategies. Agents currently under study include direct thrombin inhibitors, indirect activated factor X inhibitors, and inhibitors of tissue factor and activated factor VII. The new anticoagulant agents may demonstrate improvements in effectiveness, safety convenience and cost-effectiveness compared with current anticoagulants.