Emerging anticoagulants

Warfarin, heparin and their derivatives have been the traditional anticoagulants used for prophylaxis and treatment of venous thromboembolism. While the modern clinician is familiar with the efficacy and pharmacokinetics of these agents, their adverse effects have provided the impetus for the development of newer anticoagulants with improved safety, ease of administration, more predictable pharmacodynamics and comparable efficacy. Research into haemostasis and the coagulation cascade has made the development of these newer anticoagulants possible. These drugs include the factor Xa inhibitors and IIa (thrombin) inhibitors. Direct and indirect factor Xa inhibitors are being developed with a relative rapid onset of action and stable pharmacokinetic profiles negating the need for close monitoring; this potentially makes them a more attractive option than heparin or warfarin. Examples of direct factor Xa inhibitors include apixaban, rivaroxaban, otamixaban, betrixaban and edoxaban. Examples of indirect factor Xa inhibitors include fondaparinux, idraparinux and idrabiotaparinux. Direct thrombin inhibitors (factor IIa inhibitors) were developed with the limitations of standard heparin and warfarin in mind. Examples include recombinant hirudin (lepirudin), bivalirudin, ximelagatran, argatroban, and dabigatran etexilate. This review will discuss emerging novel anticoagulants and their use for the prophylaxis and management of venous thromboembolism, for stroke prevention in nonvalvular atrial fibrillation and for coronary artery disease.