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.