Penetration of Topically Applied Betaxolol Hcl 0.25% Ionic Suspension and Betaxolol Hcl 0.50%Solution into the Aqueous Humor

Abstract

Abstract: : Purpose: To determine the intraocular penetration of topical drops of cardio–selective beta blocker betaxolol Hcl 0.25% suspension and betaxolol Hcl 0.50% solution into the aqueous humor. Methods: This prospective randomized clinical trial comprised 19 patients having cataract surgery, all with an intact corneal epithelium. The patients were randomly assigned to receive topical betaxolol Hcl 0.25% suspension (n=7) or topical betaxolol Hcl 0.50% solution (n=8) with starting two weeks for 2x1 every day before cataract surgery. Aqueous samples were collected two to four hours after the administration of the morning dose during cataract surgery. Drug concentrations were determined by high–performance liquid chromatography (HPLC) fluorescence. Results: All patients had detectable drug concentrations in the aqueous humor measurable by HPLC. The mean aqueous humor concentration of topical betaxolol Hcl 0.25% suspension was 275.1±168.8 µg/mL (Range 570 – 70 µg/mL) and the mean aqueous humor concentration of topical betaxolol Hcl 0.50% solution was 216.1±90.5 µg/mL (Range 334 – 50 µg/mL) . Aqueous humor concentrations of topical betaxolol 0.25% suspension was higher than topical betaxolol 0.50% solution but was not statistically significant (p=0.524). Conclusions: Topical administration of betaxolol 0.25% suspension penetrated slightly better than topical betaxolol Hcl 0.50% solution to the anterior chamber but this difference was less than statistical significance.

Keywords: pharmacology • aqueous • clinical laboratory testing