Effects of topical administration of 1% brinzolamide on intraocular pressure in clinically normal horses.
Authors: Germann S E, Matheis F L, Rampazzo A, Burger D, Roos M, Spiess B M
Journal: Equine veterinary journal
Summary
Carbonic anhydrase inhibitors represent a promising but underexplored class of antiglaucoma agents in equine practice, where therapeutic options remain limited and often ineffective. Germann and colleagues administered 1% brinzolamide topically to 20 clinically normal horses using two protocols—once daily and twice daily over three-day periods—whilst measuring intraocular pressure (IOP) five times daily across a ten-day study window to establish baseline values, treatment effects, and post-treatment recovery. Once-daily dosing achieved a statistically significant IOP reduction of 3.1 mmHg (14% below baseline), whilst the twice-daily regimen produced a more substantial 5.0 mmHg reduction (21% decrease), both significant at P<0.001, with IOP returning to baseline within two days of discontinuation. Although these findings derive from normotensive eyes rather than glaucomatous patients, the dose-dependent IOP-lowering effect suggests brinzolamide warrants clinical evaluation in horses presenting with elevated intraocular pressures. For equine practitioners managing glaucoma cases—whether primary or secondary presentations—brinzolamide offers a potentially valuable topical alternative where conventional agents prove inadequate, though further studies establishing optimal dosing protocols and efficacy in diseased eyes remain essential before routine adoption into practice.
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Practical Takeaways
- •Brinzolamide 1% represents a new topical option for managing equine glaucoma, addressing the current lack of effective treatments available for horses
- •Twice-daily dosing (07.00 and 19.00 h) produces superior IOP reduction (21%) compared to once-daily treatment (14%), with both regimens showing statistical significance
- •The rapid return to baseline IOP after treatment cessation allows for flexible treatment protocols without long-term ocular complications
Key Findings
- •Once-daily 1% brinzolamide treatment reduced IOP by 3.1 mmHg (14%) from baseline in clinically normal horses (P < 0.001)
- •Twice-daily 1% brinzolamide treatment achieved greater IOP reduction of 5.0 mmHg (21%) from baseline (P < 0.001)
- •IOP returned to baseline values within 2 days of treatment cessation, indicating reversible effect
- •Brinzolamide was effective in normotensive eyes, suggesting potential efficacy in equine glaucoma cases with elevated IOP