PurposeTo determine whether intraocular pressure (IOP) lowering with fixed-combination brinzolamide/brimonidine (BBFC) adjunctive to a prostaglandin analog (PGA) was superior to that of vehicle+PGA in patients with open-angle glaucoma or ocular hypertension who were inadequately controlled with PGA monotherapyMethodsThis 6-week, multicenter, randomized, double-masked, parallel-group trial was conducted at 30 clinical sites in the United States between October 2013 and May 2014. Eligible patients were adults with open-angle glaucoma or ocular hypertension and with mean IOP ≥21 and <32 mm Hg, whereas receiving an open-label PGA (latanoprost, bimatoprost, or travoprost). Patients instilled a PGA once-daily in a run-in phase before randomization to masked BBFC or vehicle adjunctive treatment. Masked treatments were instilled 3 times daily for 6 weeks, and patients continued once-daily use of their PGA. The primary efficacy end point was the between-group difference in mean diurnal IOP (average of 0800, 1000, 1500, and 1700 hours time points) at week 6.ResultsAt week 6, mean diurnal IOP with BBFC+PGA was lower than with vehicle+PGA (17.1±0.4 mm Hg vs 20.5±0.4 mm Hg; between-group difference, -3.4±0.5 mm Hg; P<0.0001; 95% confidence interval, -4.5 to -2.4 mm Hg). BBFC+PGA reduced mean diurnal IOP by 5.7 mm Hg (25%) from the baseline IOP achieved with PGA monotherapy.ConclusionsTherapy with BBFC produced an additive IOP-lowering effect compared with a PGA alone or in conjunction with vehicle. BBFC may provide an effective treatment option for patients receiving PGA monotherapy who require additional IOP reduction.