Randomized Multicenter Clinical Trial Comparing 0.1% Brimonidine/0.5% Timolol Versus 1% Dorzolamide/0.5% Timolol As Adjuncts to Prostaglandin Analogues: Aibeta Crossover Study

Introduction This multicenter, randomized, comparative, and investigator-masked crossover clinical trial sought to compare the efficacy and tolerability of fixed combinations of 0.1% brimonidine/0.5% timolol (BTFC) versus 1% dorzolamide/0.5% timolol (DTFC) as adjunctive therapies to prostaglandin analogues. Methods A total of 110 patients with open-angle glaucoma or ocular hypertension previously treated with prostaglandin analogue monotherapy were randomized to receive either BTFC or DTFC as adjunctive therapy for 8 weeks. These patients were then crossed over to the alternative treatment arm for another 8 weeks. The reduction in intraocular pressure (IOP) (primary outcome), occurrence of adverse events, ocular discomfort after instillation, and patient preference (secondary outcomes) were recorded through patient interviews. Results BTFC instillation for 8 weeks reduced IOP by 3.55 mmHg, demonstrating non-inferiority to DTFC instillation (3.60 mmHg; P < 0.0001, mixed-effects model). Although adverse events were rare with both combinations, patients reported greater discomfort with DTFC than with BTFC ( P < 0.0001). More patients preferred BTFC ( P < 0.0001) over DTFC, as BTFC caused minimal or no eye irritation. Conclusion As BTFC offered better tolerability than DTFC with comparable reduction in IOP, we recommend it as an alternative for patients who experience ocular discomfort with DTFC-prostaglandin analogue combination therapy. Trial Registration Number jRCTs051190125.