Pharmacokinetics of PTI. One milliliter of PTI (0.5 mg/mL containing 1 × 106 cpm/mL 125I-PTI) was injected IV into each of 3 conscious rabbits. At the indicated times, blood was obtained and plasma was produced by centrifugation. The presence of PTI in each plasma sample was assessed by determination of lysis time (○) and the results are plotted as a function of time. The amount of 125I-PTI (•) in each plasma sample was also assessed and is similarly plotted. Indicated values are the mean of 3 experiments, in duplicate, in which the SEM did not exceed 8% for lysis times and 3% for radioactivity. The data indicate that the PTI concentration maximally potentiates fibrinolysis ex vivo for up to 60 minutes after its administration to the rabbit and exhibits a half-life of approximately 25 minutes.
