Activated Clotting Time (ACT) and Prothrombin Time (INR) 1 hour after injection. a: ACT, b: PT (INR). Activated clotting time (ACT) is a measure of the anticoagulation affects of heparin. So we checked the level of ACT, as well as usual blood coagulation test one hour after every injection. The dose of pentosan affected the ACT value, but the values were within a safe range. For PT (INR), the highest value was 1.47, which was weaker than the prophylactic administration of cardiovascular event.