Comparing the fixed combination brimonidine-timolol versus fixed combination dorzolamide-timolol in patients with elevated intraocular pressure

Purpose: To evaluate the efficacy of fixed combination brimonidine-timolol (FCBT) versus fixed combination dorzolamide-timolol (FCDT) given twice daily in patients with primary open angle glaucoma (POAG) or ocular hypertension (OH). Design: Prospective, multicentre, masked-observer, crossover comparison. Participants: Sixteen patients with POAG and 14 with OH. Methods: The participants of the study were washed out from their previous medication and randomized to fixed FCBT or FCDT for the first 4-week treatment period. Subjects then were washed for 4 weeks and started on the opposite medication for the second 4-week period. Intraocular pressure (1013) was measured with a Goldmann applanation tonometer at 8:00 a.m.,12:00 noon and 4:00 p.m. at each baseline and at the end of each treatment period. Unsolicited ocular adverse events were also recorded. Main outcome measures: Comparison of the IOP lowering effect of FCBT and FCDT. Results: The baseline mean diurnal IOP for all 30 subjects (30 eyes) was 22.9 +/- 1.6 mmHg. Both fixed combinations significantly reduced IOP compared with baseline (p < 0.00001). The mean diurnal IOP following 4 weeks of therapy was 15.0 +/- 2.1 mmHg for FCBT and 15.4 +/- 2.1 mmHg for FCDT (p = 0.510). The mean diurnal IOP reduction was 7.8 +/- 1.9 mmHg for FCBT and 7.4 +/- 1.8 mmHg for FCDT (p = 0.430). Overall, 14 subjects complained about ocular adverse events: two only for FCBT seven only for FCDT and five for both drugs. Although there was no significant difference between the number of subjects that reported ocular adverse events with FCBT (n = 7) and FCDT (n =12) (p= 0.359), FCDT caused more ocular stinging upon instillation (n= 9) than FCBT (n= 1) (p= 0.027). Conclusion: This study suggests that FCBT and FCDT, each given twice daily, have similar efficacy in patients with POAG or OH.