Novel oral anticoagulants and their role in clinical practice.

The complexities of oral anticoagulation with warfarin have led to the search for more practical alternative agents. Novel direct factor IIa inhibitors and direct factor Xa inhibitors currently in development can be administered at a fixed dose and do not require routine coagulation monitoring and ongoing dosage adjustment to ensure their effectiveness and safety. A number of phase III trials of these agents for the prevention of venous thromboembolism associated with orthopedic surgery and acute medical illness, for the treatment of venous thromboembolism, and for stroke prevention in patients with atrial fibrillation have been completed, with almost universally positive results. If these novel agents are approved for use in the United States, the future of oral anticoagulant therapy will allow a more nuanced approach to drug selection than has been available in the past. Attention to drug interactions and renal function will be required, as methods to measure the presence of these agents are not precise, cannot quantify the degree of anticoagulant present, and are influenced by the changes in serum drug concentrations during the dosing interval. In the future, patient preferences and the pharmacokinetic and pharmacodynamic characteristics of individual drugs will be able to be matched to optimize therapy. These new agents represent a new paradigm for anticoagulation that promises to improve patient care in the long term.