Meta-analysis of α2-adrenergic agonists versus carbonic anhydrase inhibitors as adjunctive therapy

To evaluate the efficacy of α2-adrenergic agonist (AA) brimonidine and topical carbonic anhydrase inhibitors (CAIs) dorzolamide and brinzolamide in reducing intraocular pressure (IOP) when used as adjunctive therapy to β-blockers (BBs) or prostaglandin analogs (PGAs).

Pertinent publications were identified through systematic searches of PubMed, EMBASE, and the Cochrane Controlled Trials Register. Randomized controlled trials comparing AA with CAIs in patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT) who had inadequate IOP control with monotherapy of a BB or PGA. The weighted mean differences (WMD) of IOP-lowering efficacy were calculated by performing meta-analysis.

The main efficacy measures were the reduction from baseline to end of treatment in IOP at peak, trough, and diurnal curve.

Eleven published randomized clinical trials involving 1493 patients were included in the meta-analysis. As adjunctive therapy, the IOP reduction was greater in the brimonidine group than in the CAI group at peak (WMD: 0.99 mmHg [95% confidence interval, 0.45 to 1.53]) and diurnal curve (WMD: 0.62 mmHg [0.07 to 1.18]). As adjunctive therapy to BBs, brimonidine was more effective than CAIs in reducing IOP at peak (WMD: 0.85 mmHg [0.42 to 1.29]) and trough (WMD: 0.47 mmHg [0.12 to 0.83]). As adjunctive therapy to PGAs, brimonidine resulted greater reduction in peak IOP than CAIs (WMD: 1.04 mmHg [0.08 to 2.00]).

Brimonidine provides greater IOP-lowering efficacy than topical carbonic anhydrase inhibitors as adjunctive therapy to BBs or PGAs.