Effects of Topical Omidenepag Isopropyl on Intraocular Pressure and Pupil Diameter in Normal Dogs.

Once-daily 0.002% omidenepag isopropyl significantly lowers IOP without causing miosis in healthy dogs.

This prospective, randomized, observer-masked, placebo-controlled study evaluated the effects of 0.002% omidenepag isopropyl (OMDI) ophthalmic solution on intraocular pressure (IOP) and pupil diameter (PD) in five healthy dogs (10 eyes). OMDI is a selective prostaglandin EP2 receptor agonist, representing a novel mechanistic class distinct from traditional prostaglandin F2α analogs. A pilot study first confirmed significant IOP reduction and acceptable ocular tolerability following a single instillation, with a maximal IOP reduction of 7.2 mmHg (60%) observed. In the main repeated-dose study, once-daily OMDI administration over five days significantly reduced mean daily IOP by 4.8 ± 0.68 mmHg (38.6%) compared to baseline and by 6.1 ± 0.75 mmHg (44.3%) compared to contralateral placebo-treated eyes. Importantly, no clinically relevant miosis was detected in OMDI-treated eyes, which is a notable advantage over prostaglandin F2α analogs that commonly induce miosis in dogs. Adverse effects were mild-to-moderate conjunctival hyperemia confined to treated eyes, with no serious ocular or systemic adverse events reported. IOP returned toward baseline values during the three-day recovery period. These findings suggest that once-daily topical OMDI provides robust, clinically meaningful IOP reduction with a favorable tolerability profile in normotensive dogs. The absence of miosis may offer practical advantages in glaucoma management. The authors recommend further investigations into long-term safety and efficacy specifically in canine glaucoma patients before clinical adoption.

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