A prospective open label randomised controlled trial from China compared two doses of r-tPA for massive or submassive PE. 50 mg / 2hr was as efficacious as 100 mg / 2hr but had fewer bleeding complications. Bleeding was much more common in patients under 65 kg, suggesting perhaps there should be dose per kg instead of a nice round number?
Efficacy and safety of low dose recombinant tissue-type plasminogen activator for the treatment of acute pulmonary thromboembolism: a randomized, multicenter, controlled trial.
Chest. 2010 Feb;137(2):254-62