Risk of Bleeding Fibrinolytic drugs dissolve blood clots, including those formed naturally as a protective response to vessel injury, which can result in bleeding. The risk of intracranial hemorrhaging increases as the dosage increases. Patients who are already taking other medications to prevent formation of clots, such as anticoagulants or antiplatelets, may not be good candidates for the use of fibrinolytic drugs due to the increased difficulty of controlling bleeding. In the study that led to FDA approval of rt-PA, the incidence of SICH in rt-PA patients was 6.4%, compared to 0.6% in the placebo group. As a result, rt-PA is subject to strict limitations on when, how long and in what dosages it may be administered