A short term study of the additive effect of timolol and brimonidine on intraocular pressure.

Objective: To evaluate the additive ocular hypotensive effect of the combination of brimonidine and timolol on intraocular pressure (IOP) reduction in patients with glaucoma.

Methods: This was a prospective, randomized, double-masked, crossover study in 20 patients with primary open angle glaucoma (POAG) on therapy receiving timolol maleate 0.5% twice daily, with IOP greater than or equal to 22 mmHg in one eye. The treatment period was 3 weeks and during this period timolol + brimonidine or timolol + placebo were applied topically twice daily and IOP, blood pressure, heart rate and pupil size were measured.

Results: Combined therapy (timolol + brimonidine) had clinically significant IOP-lowering effect during the treatment period P << 0.01). The mean diurnal IOP was significantly reduced by an average of 5.1-5.9 mmHg (21.2-24.5%) compared with baseline value. The timolol + placebo combination had no clinically significant IOP-lowering effect (P > 0.05). No clinically significant side effects were observed during the treatment of both groups.

Conclusions: This study showed that the combination of topically applied brimonidine and timolol cause a marked and sustained IOP reduction.