Efficacy of brimonidine 0.2% and dorzolamide 2% as adjunctive therapy to beta-blockers in adult patients with glaucoma or ocular hypertension.
BACKGROUND
The alpha-adrenergic agonist brimonidine and the carbonic anhydrase inhibitor dorzolamide have been studied both as monotherapy and in combination with beta-blockers in the treatment of glaucoma and ocular hypertension; however, a MEDLINE literature search failed to reveal any clinical studies directly comparing these 2 agents as adjunctive therapy.


OBJECTIVE
The purpose of this study was to compare the intraocular pressure (IOP)-lowering efficacy of brimonidine and dorzolamide as adjunctive therapy to beta-blockers in adult patients with glaucoma or ocular hypertension.


METHODS
In a prospective, investigator-masked, multicenter, parallel-design clinical trial, adult patients whose IOP was inadequately controlled with topical beta-blocker therapy were randomly assigned to receive brimonidine 0.2% twice daily or dorzolamide 2% 3 times daily as adjunctive therapy for 3 months. Efficacy was determined by the reduction in IOP from baseline. After 1 month of adjunctive treatment, patients who failed to meet a target 15% reduction in IOP at peak drug effect were crossed over to the other study medication.


RESULTS
A total of 106 patients were treated. Approximately 70% (74/106) of the patients were white, and 61.3% (65/106) had a diagnosis of open-angle glaucoma. Mean baseline IOP (ie, with beta-blocker monotherapy) was comparable between treatment groups (approximately 21 mm Hg). After 1 month of adjunctive treatment, the mean daily IOP reduction was significantly greater with brimonidine (4.40 mm Hg, 20.4%) than with dorzolamide (3.0 mm Hg, 14.4%, P = 0.033). At peak drug effect at month 1, the mean IOP reduction was significantly greater in the brimonidine group (5.95 mm Hg, 27.6%) than in the dorzolamide group (4.11 mm Hg, 19.7%; P = 0.007). Significantly more patients treated with brimonidine (44/51, 86.3%) than with dorzolamide (29/47, 61.7%) achieved the target 15% reduction in IOP at month 1 (P = 0.005). At month 3, the mean daily IOP reduction and the mean IOP reduction at peak drug effect were not significantly different in the 2 treatment groups. The mean daily IOP reduction was 4.98 mm Hg in the brimonidine group and 3.15 mm Hg in the dorzolamide group (P = 0.092). At peak drug effect, the mean IOP reduction was 6.39 mm Hg with brimonidine and 4.06 mm Hg with dorzolamide. The incidence of adverse events leading to discontinuation was 9.3% (5/54) in the brimonidine group (depression, 2; allergic conjunctivitis, 1; dry mouth and tearing, 1; dermatitis, 1) and 9.8% (5/51) in the dorzolamide group (ocular burning and stinging, 2; ocular itch, 1; gastrointestinal complaints, 1; lack of tolerance for beta-blocker, 1), with no significant difference between groups.


CONCLUSIONS
In this trial, brimonidine 0.2% twice daily produced greater mean decreases in IOP and was effective in more patients than dorzolamide 2% 3 times daily when used as adjunctive therapy to beta-blockers.
Simmons
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Glaucoma Consultants of the Capital Region, Slingerlands, New York 12159-9222, USA.
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D000068438:Brimonidine Tartrate; D018592:Cross-Over Studies; D015536:Down-Regulation; D005260:Female; D005901:Glaucoma / Q000188:drug therapy*; D006801:Humans; D007155:Immunologic Factors / Q000008:administration & dosage / Q000627:therapeutic use*; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy*; D011788:Quality of Life; D011810:Quinoxalines / Q000008:administration & dosage / Q000627:therapeutic use*; D013449:Sulfonamides / Q000008:administration & dosage / Q000627:therapeutic use*; D013876:Thiophenes / Q000008:administration & dosage / Q000627:therapeutic use*
D000319:Adrenergic beta-Antagonists; D000959:Antihypertensive Agents; D007155:Immunologic Factors; D011810:Quinoxalines; D013449:Sulfonamides; D013876:Thiophenes; D000068438:Brimonidine Tartrate; C062765:dorzolamide