Making anticoagulation safer

[...]their use also leads to substantial increases in major and minor bleeding.1,2 This is not surprising; FXa and thrombin are at the core of the system that stems bleeding after blood vessel injury. Despite its limited role in haemostasis, there is compelling evidence that FXI contributes to thrombosis, and particularly to venous thromboembolism and ischaemic stroke.6 In phase 2 studies with patients undergoing knee replacement, lowering plasma FXI or inhibiting FXIa reduced the incidence of postoperative venous thromboembolism as well as, or better than, standard treatment.7–10 However, although these studies showed that FXI or FXIa inhibition reduces thrombosis in a specific clinical setting, they were not designed to study the effect on bleeding. Furthermore, the number of bleeding events was only half of the anticipated number (ten compared with 20 events), and no major bleeding events were observed. [...]although asundexian is likely to have caused less bleeding than apixaban, the results did not allow the magnitude of the effect to be accurately determined.