There are three major classes of fibrinolytic drugs: tissue plasminogen activator (tPA), streptokinase (SK), and urokinase (UK).
Tissue plasminogen activator (tPA, tissue-type plasminogen activator) is a serine protease found on endothelial cells. tPA enzyme catalyzes the conversion of plasminogen to plasmin.
The major physiological function of t-PA is to generate plasmin that can dissolve blood clots in the vasculature. Recent studies suggest that reduced t-PA activity and elevated t-PA and PAI-1 antigen levels may be a risk marker for cardiovascular disease.