Effect of topical administration of 2% dorzlamide hydrochloride or 2% dorzlamide hydrochloride-0.5% timolol maleate on intraocular pressure in clinically normal horses.
OBJECTIVE
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.
Willis
A M
AM
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus 43210, USA.
Robbin
T E
TE
Hoshaw-Woodard
S
S
Wilkie
D A
DA
Schmall
M L
ML
D000287:Administration, Topical; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D002626:Chemistry, Pharmaceutical; D004338:Drug Combinations; D005260:Female; D006736:Horses / Q000502:physiology*; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D011897:Random Allocation; D012044:Regression Analysis; D013449:Sulfonamides / Q000008:administration & dosage / Q000494:pharmacology*; D013876:Thiophenes / Q000008:administration & dosage / Q000494:pharmacology*; D013999:Timolol / Q000008:administration & dosage / Q000494:pharmacology*
D000319:Adrenergic beta-Antagonists; D002257:Carbonic Anhydrase Inhibitors; D004338:Drug Combinations; D013449:Sulfonamides; D013876:Thiophenes; D013999:Timolol; C062765:dorzolamide