Effects of topical administration of 1% brinzolamide on normal cat eyes

Objective  To evaluate the effect of short-term daily topical administration of 1% brinzolamide on the intraocular pressure (IOP) of healthy domestic cats with normotensive eyes and to assess the potential for negative side effects of drug administration. Animals  Twelve privately owned adult domestic cats without physical or ocular abnormalities. Procedure  Normal variation in IOP was determined on day 1. Cats were then treated on days 2–8 with a topical placebo (artificial tear solution) OU q 12 h. On days 9–15 the cats were treated q 12 h with 1% brinzolamide in one randomly selected eye and the placebo in the contralateral eye. All medications (drug and placebo) were administered twice daily at 7 a.m. and 7 p.m. On days 16–22 the cats received no topical medications. IOP, horizontal pupil size in mm and assessment of conjunctival hyperemia were noted OU on days 1, 8, 15 and 22 at 5 time points (9 a.m., 11 a.m., 1 p.m., 3 p.m. and 5 p.m.). Mixed linear regression models were used to compare the IOP of each eye at all time periods for each cat, controlling for age and weight. Results  Mean IOP was not significantly altered in any eye at any time point during the treatment period compared with pretreatment, baseline, or follow-up evaluations. Conjunctival hyperemia and miosis were not detected in either eye at any time point. Conclusions and clinical relevance Short-term q 12 h administration of 1% brinzolamide did not significantly reduce IOP in this small sample population of normotensive cats under these study conditions. No clinically relevant side effects were noted with brinzolamide administration.