Evaluation of intraocular penetration of topically administered tissue plasminogen activator in dogs

Topically administered tissue plasminogen activator (tPA) was evaluated for its penetration into aqueous humor of clinically normal dogs. Two concentrations of tPA (5 mg/ml and 10 mg/ml) were evaluated in a single-dose study, and a concentration of 5 mg of tPA/ml was used for a multiple-dose study. The contralateral eye served as a nontreated control. Enzyme substrate analysis of aqueous humor was used to determine tPA activity. The activity of tPA in aqueous humor was significantly (P < or = 0.05) greater in treated eyes of all dogs, compared with that in control eyes. Significant differences in activity of tPA were not detected at different doses in treated eyes.