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Abstract #6364 Published in IGR 3-2
Changes in intraocular pressure associated with topical dorzolamide and oral methazolamide in glaucomatous dogs
Gelatt KN; MacKay EOVeterinary Ophthalmology 2001; 4: 61-67
OBJECTIVE: To compare the reduction in intraocular pressure (IOP) by topical 2% dorzolamide to oral methazolamide (5 mg/kg) in dogs, and determine if the combination of both drugs would reduce IOP more than either drug administered alone. ANIMALS STUDIED: Thirteen glaucomatous beagles. PROCEDURES: Measurements, including applanation tonometry, pupil size and heart rate, were obtained at 8 a.m., 12 noon, and 5 p.m. on days 1, 3 and 5. The five-day drug studies included placebo (0.5% methylcellulose); 2% dorzolamide administered in one eye twice daily (8 a.m. and 5 p.m.), and repeated again in one eye three times (8 a.m., 12 noon and 5 p.m.) daily; methazolamide (5 mg/kg per os administered at 8 a.m. and 5 p.m.); 2% dorzolamide instilled twice daily (five days) combined with oral methazolamide on the last three days, and methazolamide (five days) combined with 2% dorzolamide on the last three days and instilled twice daily. Statistical comparisons between drug groups included control (nondrug) eye and treated (placebo/drug) eyes for days 1, 3, and 5. RESULTS: Topical 2% dorzolamide, administered twice and three times daily, significantly decreased IOP (mean ± SEM) in glaucomatous dogs on the first day (twice daily 7.6 ± 2.4 mmHg, and three times daily 16.4 ± 3.6 mmHg) that was even greater by day 5 (twice daily 10.4 ± 2.0 mmHg, and three times daily 13.9 ± 2.7). Oral methazolamide also significantly lowered IOP in both eyes. Oral methazolamide (administered from days 1 through 5) combined with 2% topical dorzolamide (instilled in the drug eye for days 3 through 5) also significantly lowered IOP of both eyes for all days, and for day 5 the mean ± SEM IOP was decreased by 7.9 ± 1.7 mmHg (methazolamide plus dorzolamide) and 7.5 ± 2.6 mmHg (methazolamide only). Topical dorzolamide (instilled in the drug eye for days 1 through 5) combined with oral methazolamide (administered from days 3 through 5) significantly lowered IOP in the drug eye on day 1 (5 p.m.: 9.6 ± 1.9 mmHg), for day 3 (11 a.m. and 5 p.m.) and for all of day 5 for both eyes (5 p.m.: control eye 9.5 ± 1.8 mmHg; drug eye 9.2 ± 1.9 mmHg). Topical dorzolamide (2%) instilled three times daily produces similar IOP declines compared to the combination of oral methazolamide and 2% dorzolamide administered twice daily. CONCLUSIONS: Dorzolamide (2%) instilled twice or three times daily causes significant decreases in IOP in glaucomatous dogs. Twice daily instillations caused progressive declines in IOP from day 1 to day 5. Dorzolamide (2%) combined with oral methazolamide (5 mg/kg per os twice daily) produces similar but not additional declines in IOP.
Dr K.N. Gelatt, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0126, USA. gelattk@mail.vetmed.ufl.edu
Classification:
5 Experimental glaucoma; animal models
11.5.2 Topical (Part of: 11 Medical treatment > 11.5 Carbonic anhydrase inhibitors)
