Purpose: Oral carbonic anhydrase inhibitors used to treat glaucoma have significant systemic side effects. Brinzolamide 1.0%, a new topical ocular carbonic anhydrase inhibitor, is effective apparently without significant systemic side effects. This study was performed to establish the long-term safety and efficacy of brinzolamide 1.0% two and three times daily for primary open-angle glaucoma and ocular hypertension.
Methods: An 18-month, multicenter, double-masked, parallel, controlled study was conducted. Patients were randomized to brinzolamide two or three times daily or timolol 0.5% twice daily in a 2:2:1 ratio (n = 150, 153, and 75, respectively). Intraocular pressure was measured at 8:00 AM at eligibility and months 1, 3, 6, 9, 12, 15, and 18. Efficacy was based on intraocular pressure reduction from baseline. Safety was also evaluated.
Results: All regimens produced clinically relevant and statistically significant (P<.05) intraocular pressure reductions from baseline. Mean changes in intraocular pressure trough measurements ranged from -2.7 to -3.9 mm Hg with brinzolamide twice-daily dosing and -2.8 to -3.8 mm Hg three times daily dosing compared with -4.7 to -5.6 mm Hg with timolol. The intraocular pressure reductions with brinzolamide two and three times daily were clinically and statistically equivalent. One hundred forty-four patients were discontinued from the study after randomization with the most common reasons being the occurrence of an adverse event (46), inadequate intraocular pressure control (23), patient decision unrelated to study medication (11), lost to follow-up (16), and noncompliance (9). Adverse events were nonserious and resolved without sequelae. There were no clinically relevant changes in safety parameters. Brinzolamide produced less ocular discomfort (burning/stinging) than timolol, and total carbonic anhydrase inhibition levels remained below that known to cause systemic side effects.
Conclusion: Brinzolamide produced significant and equivalent reductions in intraocular pressure when dosed two and three times daily for 18 months. Brinzolamide was safe and well tolerated by patients, with minimal ocular discomfort.