ISTA Reports Two Preliminary Results Of T-Pred Studies

ISTA Pharmaceuticals (ISTA) has reported preliminary results from two recently completed studies on its investigational ophthalmic product, T-Pred (prednisolone acetate 1.0% and tobramycin 0.3% ophthalmic suspension).

Reportedly, the company is developing T-Pred as a treatment for inflammatory ocular conditions for which a corticosteroid is indicated and where bacterial ocular infection exists, or there is a risk of bacterial infection.

In the first study, ISTA evaluated the antimicrobial equivalence between T-Pred and a tobramycin-containing reference product. In-vitro tests were conducted to compare the kill rate of T-Pred with the kill rate of the reference product for each of the micro-organisms listed in the reference product’s package insert as well as additional micro-organisms specified by the FDA.

ISTA has successfully demonstrated the antimicrobial bioequivalence of T-Pred to the reference product in each of the 26 required tests.

However, the second study was a phase 3 clinical study designed to determine the bioequivalence of prednisolone concentrations between T-Pred and a reference product containing prednisolone acetate 1.0%.

The multi-center, randomised, double-masked study enrolled 172 patients undergoing bilateral cataract removal. Patients served as their own internal control in the study, receiving one drop of either T-Pred or the prednisolone reference product prior to cataract extraction.

Aqueous humor sampling was performed at one of four assigned time points. In order to demonstrate the bioequivalence of the two products, the ratio of calculated prednisolone values in aqueous humor needed to fall between 80% and 125%, with a 90% confidence interval for the ratios during all time points measured.

The company is working with the FDA to determine the appropriate clinical study or studies to perform in lieu of an additional prednisolone bioequivalence study, although no further clinical studies are planned before 2010.