Effect of brinzolamide and dorzolamide on aqueous humor flow in human eyes

• Published in: American journal of ophthalmology 1999-09, Vol.128 (3), p.292-296
• Main Authors: Ingram, Cory J., Brubaker, Richard F.
• Format: Article
• Language: English
• Subjects: Adult; Aqueous Humor - drug effects; Aqueous Humor - metabolism; Biological and medical sciences; Carbonic Anhydrase Inhibitors - administration & dosage; Carbonic Anhydrase Inhibitors - pharmacology; Double-Blind Method; Drug Evaluation; Eye; Female; Fluorescein - metabolism; Fluorophotometry; Humans; Intraocular Pressure - drug effects; Male; Medical sciences; Ophthalmic Solutions - administration & dosage; Ophthalmic Solutions - pharmacology; Pharmacology. Drug treatments; Sulfonamides - administration & dosage; Sulfonamides - pharmacology; Thiazines - administration & dosage; Thiazines - pharmacology; Thiophenes - administration & dosage; Thiophenes - pharmacology
• ISSN: 0002-9394; 1879-1891
• DOI: 10.1016/S0002-9394(99)00179-8

PURPOSE: To measure the relative efficacy of brinzolamide hydrochloride 1% ophthalmic suspension, a new carbonic anhydrase inhibitor, compared with the currently used dorzolamide hydrochloride 2% ophthalmic solution as suppressors of aqueous humor flow in human eyes, and to study the difference of effect during the day and at night. METHODS: A randomized, double-masked, placebo-controlled study of 25 normal human subjects was carried out at Mayo Clinic. The daytime rate of aqueous humor flow was measured every 2 hours from 8 am to 4 pm by means of fluorophotometry. Likewise, the nighttime rate of aqueous humor flow was measured every 2 hours from 12 am to 6 am. Intraocular pressure was measured at 4 pm and 6 am. RESULTS: Brinzolamide reduced aqueous flow by 0.47 ± 0.20 μl per min (mean ± SD) during the day, whereas dorzolamide reduced flow by 0.34 ± 0.20 μl per min. Brinzolamide reduced aqueous flow by 0.16 ± 0.12 μl per min during the night, whereas dorzolamide reduced flow by 0.10 ± 0.13 μl per min. Brinzolamide reduced afternoon intraocular pressure by 1.5 ± 1.1 mm Hg, and dorzolamide reduced afternoon intraocular pressure by 1.1 ± 1.0 mm Hg. Brinzolamide reduced the morning awakening intraocular pressure by 0.3 ± 1.6 mm Hg, and dorzolamide reduced it by 0.8 ± 1.0 mm Hg. CONCLUSIONS: Our data support the idea that brinzolamide is at least as efficacious as dorzolamide as a suppressor of aqueous humor flow in normal human eyes and that there is probably not a clinically significant difference between the two drugs in this efficacy. Clinicians who prescribe brinzolamide should expect similar ocular hypotensive responses from brinzolamide and dorzolamide.