Penetration of betaxolol HCL ionic suspension 0.25% and betaxolol HCL solution 0.50% into the aqueous humor

PURPOSE. To determine the intraocular penetration of topical drops of betaxolol HCl 0.25% suspension and betaxolol HCl 0.50% solution into the aqueous humor. METHODS. Fifteen patients were randomly assigned to receive topical betaxolol HCl 0.25% suspension (n=7) or topical betaxolol HCl 0.50% solution (n=8) the day before cataract surgery. Aqueous samples were collected 2 hours after the administration of the morning dose during cataract surgery. Drug concentrations were determined by high-performance liquid chromatography with fluorescence detection. RESULTS. 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 195.4±102.4 μg/mL (range 334-50 μg/mL) (p=0.281). CONCLUSIONS. The mean aqueous humor concentration of betaxolol 0.25% suspension was higher than betaxolol 0.50% solution; however, the difference was not statistically significant. With twofold reduced concentration and similar anterior chamber penetration, betaxolol 0.25% suspension could be first choice for β1 selective blocker therapy when considered for patients with glaucoma.