Effects of topical 2% dorzolamide hydrochloride alone and in combination with 0.5% timolol maleate on intraocular pressure in normal feline eyes.
OBJECTIVE
To evaluate the effect of topical 2% dorzolamide alone, and in combination with topical 0.5% timolol, on intraocular pressure (IOP) in normal cats.


METHODS
Twenty-four healthy Domestic Short-haired cats.


METHODS
Baseline values of IOP were established at 7 am, 10 am, 1 pm, 5 pm and 9 pm during pretreatment phase (days 1-2). During treatment phase (days 3-10) cats received 2% dorzolamide HCl q 12 h in group A (n = 6), q 8 h in group B (n = 6), and combined with 0.5% timolol maleate q 12 h in group C (n = 6). Cats in control group D (n = 6) received artificial tears q 8 h. During treatment phase IOP measurements were continued at the same time-points as in the pretreatment phase.


RESULTS
Mean pretreatment IOP in all cats was 18.46 +/- 2.99 mmHg. Mean IOP decreased significantly (P < 0.0086) in all treatment groups compared to pretreatment values (group A: 16.40 +/- 0.49 mmHg, group B: 16.04 +/- 0.49 mmHg, group C: 17.76 +/- 0.49 mmHg). IOP did not decrease in control group D (18.55 +/- 0.49 mmHg). The difference in IOP between treatment groups (A, B, C) was not statistically significant, but comparison of IOP between each treatment group and the control group was statistically significant (A-D; P = 0.0057; B-D, P = 0.0012; C-D, P = 0.0212).


CONCLUSIONS
Topical 2% dorzolamide significantly lowers IOP in normal cats but the effect is mild. Concomitant application of 2% dorzolamide and 0.5% timolol does significantly decrease IOP, but the effect is not significantly greater than q 8 h administration of dorzolamide alone.
Dietrich
Ursula M
UM
Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, The University of Georgia, Athens, GA 30602, USA. dietrich@vet.uga.edu
Chandler
Matthew J
MJ
Cooper
Tanya
T
Vidyashankar
Anand
A
Chen
Guorong
G
D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002415:Cats; D004359:Drug Therapy, Combination; D005260:Female; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000494:pharmacology*; D013449:Sulfonamides / Q000008:administration & dosage / Q000494:pharmacology*; D013876:Thiophenes / Q000008:administration & dosage / Q000494:pharmacology*; D013999:Timolol / Q000008:administration & dosage / Q000494:pharmacology*; D014065:Tonometry, Ocular / Q000662:veterinary; D016896:Treatment Outcome
D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013876:Thiophenes; D013999:Timolol; C062765:dorzolamide