Effect of topical administration of 2% dorzlamide hydrochloride or 2% dorzlamide hydrochloride-0.5% timolol maleate on intraocular pressure in clinically normal horses.
Abstract: To evaluate the effect of topical administration of 2% dorzolamide hydrochloride or 2% dorzolamide hydrochloride-0.5% timolol maleate on intraocular pressure (IOP) in clinically normal horses. Methods: 18 healthy adult horses without ocular abnormalities. Methods: The IOP was measured at 5 time points (7 AM, 9 AM, 11 AM, 3 PM, 7 PM) over 11 days. On days 1 and 2, baseline values were established. On days 3 through 5, horses received 2% dorzolamide HCI (group D, n = 9) or 2% dorzolamide HCl-0.5% timolol maleate (group DT, 9) in 1 randomly assigned eye every 24 hours immediately following each daily 7 AM IOP measurement. On days 6 through 9, each drug was given every 12 hours (7 AM and 7 PM) in the treated eye. Measurements on days 10 and 11 assessed return to baseline. Mixed linear regression models compared mean IOP difference for each drug at each time period. Results: Mean IOP decreased significantly in all eyes during the 2 dose/d period, compared with the baseline, 1 dose/d, and follow-up periods. Conclusions: Administration of either drug every 24 hours for short-term treatment does not reduce IOP significantly. Administering either drug every 12 hours induced a significant reduction of IOP; however, controlling for all variables, the reduction was less than 2 mm Hg.
Publication Date: 2001-05-09 PubMed ID: 11341390DOI: 10.2460/ajvr.2001.62.709Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research examines the impact of two different ophthalmic drugs, dorzolamide hydrochloride and a combination of dorzolamide hydrochloride and timolol maleate, on intraocular pressure in horses.
Objective and Methodology
- The main objective was to test the efficacy of 2% dorzolamide hydrochloride and a combination of 2% dorzolamide hydrochloride and 0.5% timolol maleate in reducing intraocular pressure (IOP) in horses.
- An experiment was conducted over 11 days with 18 healthy adult horses which have no ocular abnormalities. The IOP measurements were taken at five specific time points throughout each day.
- During the first two days, baseline values for IOP were established. For the next three days, horses were randomly assigned to either receive dorzolamide alone (group D) or the combination treatment (group DT) once every 24 hours.
- Between days 6 through 9, dosage frequency increased to twice a day (at 7 AM and 7 PM). Post-treatment IOP measurements were taken on days 10 and 11 to ascertain any return to baseline values.
Results
- Findings showed a significant decrease in mean IOP during the period when the drugs were administered twice a day, compared to the baseline readings, periods when single doses were given, and the follow-up period.
Conclusions
- The study concluded that short-term treatment of either drug every 24 hours does not significantly reduce IOP. However, administering either drug every 12 hours led to a significant reduction in IOP.
- Notwithstanding, the researchers pointed out that after controlling for all variables, the reduction was less than 2 mm Hg, suggesting the decreases were slight yet statistically significant.
Implication
- This study implies that for either 2% dorzolamide hydrochloride or the combination medication to have a significant effect on lowering IOP in horses, it may need to be administered twice daily. These findings could help guide veterinary eye care procedures and treatment plans.
Cite This Article
APA
Willis AM, Robbin TE, Hoshaw-Woodard S, Wilkie DA, Schmall ML.
(2001).
Effect of topical administration of 2% dorzlamide hydrochloride or 2% dorzlamide hydrochloride-0.5% timolol maleate on intraocular pressure in clinically normal horses.
Am J Vet Res, 62(5), 709-713.
https://doi.org/10.2460/ajvr.2001.62.709 Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus 43210, USA.
MeSH Terms
- Administration, Topical
- Adrenergic beta-Antagonists / administration & dosage
- Adrenergic beta-Antagonists / pharmacology
- Animals
- Carbonic Anhydrase Inhibitors / administration & dosage
- Carbonic Anhydrase Inhibitors / pharmacology
- Chemistry, Pharmaceutical
- Drug Combinations
- Female
- Horses / physiology
- Intraocular Pressure / drug effects
- Male
- Random Allocation
- Regression Analysis
- Sulfonamides / administration & dosage
- Sulfonamides / pharmacology
- Thiophenes / administration & dosage
- Thiophenes / pharmacology
- Timolol / administration & dosage
- Timolol / pharmacology
Citations
This article has been cited 3 times.- Rizzo D. Idiopathic glaucoma in an 11-year-old crossbred mare. Can Vet J 2017 May;58(5):508-510.
- Gemensky-Metzler AJ, Wilkie DA, Weisbrode SE, Kuhn SE. The location of sites and effect of semiconductor diode trans-scleral cyclophotocoagulation on the buphthalmic equine globe. Vet Ophthalmol 2014 Jul;17 Suppl 1(0 0):107-16.
- Tucker-Retter EK, Yamagata M, Gilger B, Oh A. Retrospective Assessment of Carbonic Anhydrase Inhibitors in Topical or Episcleral Implant Form for the Treatment of Equine Glaucoma. Vet Ophthalmol 2025 Nov;28(6):977-982.
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