Comparing diurnal and nocturnal effects of brinzolamide and timolol on intraocular pressure in patients receiving latanoprost monotherapy.

Purpose: To compare the diurnal and nocturnal effects of brinzolamide and timolol on intraocular pressure (IOP) in patients already receiving monotherapy with latanoprost.

Design: Prospective, open-label, and crossover clinical trial.

Participants: Twenty-six patients with glaucoma or ocular hypertension (ages, 44-79 years) who were receiving treatment with 0.005% latanoprost once every evening.

Methods: Baseline data of 24-hour IOP were collected in a sleep laboratory while patients were receiving latanoprost monotherapy. Measurements were taken every 2 hours in the sitting and supine positions during the 16-hour diurnal/wake period and in a supine position during the 8-hour nocturnal/sleep period. Patients were randomly assigned to receive an add-on treatment with either 1% brinzolamide 3 times per day or 0.5% timolol gel forming solution once every morning for 8 weeks, and then crossed over to receive the other add-on treatment. At the end of each add-on treatment period, 24-hour IOP data were collected.

Main Outcome Measures: Diurnal and nocturnal IOP means were compared among the baseline, the brinzolamide add-on treatment, and the timolol add-on treatment.

Results: During the diurnal period, the mean IOP under brinzolamide or timolol add-on treatment was significantly lower than the baseline IOP in both the sitting and supine positions. There was no statistical difference between the 2 add-on treatments. During the nocturnal period, the supine IOP under brinzolamide add-on treatment was significantly lower than both the baseline and the timolol add-on treatment. There was no difference in nocturnal IOP between the timolol add-on treatment and the baseline.

Conclusions: In patients already receiving the latanoprost monotherapy, adding brinzolamide or timolol significantly reduced IOP during the diurnal period. However, only the brinzolamide add-on treatment had an IOP-lowering efficacy during the nocturnal period.