Original article
Brimonidine 0.2% versus dorzolamide 2% each given three times daily to reduce intraocular pressure

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Abstract

PURPOSE: To evaluate the efficacy and safety of brimonidine compared with dorzolamide given three times daily as monotherapy in patients with primary open-angle glaucoma or ocular hypertension.

METHODS: In a double-masked, multicenter, crossover comparison in 40 patients, qualified patients were washed out from their previous medication and randomized to dorzolamide 2% or brimonidine 0.2% for the first 6-week treatment period. Patients then were washed out for 2 weeks and started on the opposite medication for the second 6-week period.

RESULTS: Baseline intraocular pressure for all 40 subjects (76 eyes) was 24.1 ± 2.0 mm Hg. This study found that the 8:00 am trough intraocular pressure after 6 weeks of therapy for dorzolamide was 20.7 ± 3.1 mm Hg and for brimonidine 20.8 ± 3.2 mm Hg (P = .99). The peak intraocular pressure (2 hours after dosing) for dorzolamide was 18.6 ± 3.4 mm Hg and for brimonidine 17.8 ± 2.7 mm Hg (P = .10 ). Dorzolamide caused more stinging upon instillation (P < .01) and brimonidine more itching (P = .01). No statistical differences existed between groups for systemic adverse events. Six patients, all on brimonidine, were discontinued from a treatment period early. Of these, two were discontinued for inadequate pressure control, two with dizziness and fatigue, one with ocular pain, and one for lifestyle reasons (P = .07).

CONCLUSIONS: This study found similar efficacy and safety between monotherapy treatment with dorzolamide or brimonidine when each was given three times daily to patients with ocular hypertension or primary open-angle glaucoma.

Section snippets

Methods

In this study we included patients who met the following inclusion criteria: 18 years of age or older, a clinical diagnosis of primary open-angle glaucoma or ocular hypertension in at least one eye (study eye), an intraocular pressure controllable on one drug therapy in the study eye(s) in such a way that ensured clinical stability of vision and the optic nerve throughout the trial, baseline intraocular pressure of 22 to 34 mm Hg in the study eye(s) (in eyes not included in the study, the

Results

We enrolled 42 patients in this crossover comparison. Two patients withdrew consent during a study period (see below under adverse events). Of patients finishing the trial, 24 had ocular hypertension and 16 primary open-angle glaucoma. Twenty-three were female and 17 male; 21 were white and 19 black. The average age was 57.7 ± 13.3 years.

Baseline intraocular pressure for all 40 patients was 24.1 ± 2.0 mm Hg. After 6 weeks of therapy the trough intraocular pressure for the dorzolamide group was

Discussion

Dorzolamide 2% is a topical carbonic anhydrase inhibitor that was released in 1995 by Merck to provide a safer alternative to the oral carbonic anhydrase inhibitor, acetazolamide, in the treatment of primary open-angle glaucoma or ocular hypertension. Dorzolamide has been a popular adjunctive agent and frequently is used as monotherapy. Dosing for dorzolamide is labeled three times daily, but it may be tried twice daily.6 Dorzolamide reduces the intraocular pressure by 10% to 26% as a

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This work was sponsored by an unrestricted grant from Merck, Inc, and in part by an unrestricted grant from Research to Prevent Blindness, Inc.

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