Factor XI and XIa inhibition: a new approach to anticoagulant therapy.

Factor (F) XI or XIa inhibition has Fattracted interest due to the protection from thrombotic events and minimal bleeding tendency observed in FXI-deficient individuals. The prospect of uncoupling the management of thrombosis from the bleeding risk inadvertently associated with current therapy inspired the development of agents directed towards this step in the coagulation process. This review describes the physiological rationale behind FXI/FXIa inhibition and the pharmacological properties of existing FXI/FXIa inhibitors. It also explores the potential clinical use of these agents in various thromboembolic pathologies, predominantly through the phase II clinical trials conducted so far comparing them to current anticoagulant therapy or placebo.