Introduction: This study compared the efficacy and safety of adjunctive brimonidine tartrate 0.1% ophthalmic solution (brimonidine) and timolol maleate 0.5% ophthalmic solution (timolol) in prostaglandin analogue (PGA)-treated normal-tension glaucoma (NTG), assessing the non-inferiority of brimonidine in terms of intraocular pressure (IOP) reduction.
Methods: In this multicenter, randomized, investigator-masked, parallel-group, clinical study, adjunctive brimonidine or timolol was administered twice daily for 12 weeks in eyes with NTG that had been treated with PGA for at least 90 days and required additional treatment despite an IOP of 16 mmHg or less. IOP was measured on at least three visits before add-on therapy (mean baseline IOP), and at weeks 4, 8, and 12 after adjunctive administration. Systolic/diastolic blood pressure, pulse rate, and adverse events (AEs) were recorded at each visit.
Results: A total of 152 individuals were enrolled and 128 (84.2%) were eligible for efficacy analyses. IOP in both groups at each visit decreased significantly from baseline (P < 0.001). However, the difference in the change from baseline IOP at week 12 between the brimonidine (-1.05 ± 1.81 mmHg) and timolol (-1.41 ± 1.40 mmHg) groups was 0.36 mmHg (95% confidence interval [CI] [-0.21, 0.92]), which exceeded the value of the non-inferiority margin (0.75 mmHg). Baseline systolic/diastolic blood pressure decreased significantly in both groups at certain visits (P < 0.05), while baseline pulse rates decreased significantly in the timolol group (P < 0.001), with no significant differences in the brimonidine group. AE-related treatment discontinuation occurred in 2/71 (2.8%) and 2/75 (2.7%) patients in the brimonidine and timolol groups, respectively.
Conclusion: This study demonstrated an add-on effect of brimonidine to PGAs, although non-inferiority of brimonidine to timolol as adjunctive therapy in PGA-treated NTG in terms of IOP reduction was not observed. Brimonidine was associated with no adverse effects on pulse rate.
Funding: Senju Pharmaceutical Co., Ltd.
Trial registration: UMIN Clinical Trials Registry identifier, UMIN000014810.
Keywords: Brimonidine; Glaucoma; Intraocular pressure; Ophthalmology; Prostaglandin analogues; Timolol.