Study explores omidenepag isopropyl’s ocular effects in dogs
Bottom line
A small prospective study in Veterinary Ophthalmology suggests topical omidenepag isopropyl, an EP2 receptor agonist used in human glaucoma care, may lower intraocular pressure in clinically normal dogs without meaningfully changing pupil diameter. The randomized, observer-masked, placebo-controlled study enrolled five healthy dogs, with each eye assigned to either 0.002% omidenepag isopropyl or placebo after an initial pilot phase assessing short-term pressure changes and ocular irritation. Omidenepag isopropyl is already approved in the U.S. for reducing elevated intraocular pressure in people with open-angle glaucoma or ocular hypertension, marketed as Omlonti. (dailymed.nlm.nih.gov)
Why it matters: For veterinary ophthalmologists and general practitioners managing canine glaucoma, the paper adds early species-specific data on a drug class that works through prostaglandin E2 EP2 signaling rather than the FP receptor pathway used by latanoprost. That distinction matters because omidenepag has drawn interest as a potential alternative mechanism for lowering pressure, and human literature suggests it may avoid some prostaglandin-associated cosmetic effects, though conjunctival hyperemia remains a known issue. Still, this was a very small study in normal dogs, not dogs with glaucoma, so it should be read as proof-of-concept rather than practice-changing evidence. (pubmed.ncbi.nlm.nih.gov)
What to watch: The next key question is whether larger trials in dogs with naturally occurring glaucoma can show clinically meaningful pressure control, safety, and durability versus established options such as latanoprost or combination therapy. (onlinelibrary.wiley.com)
Key facts
- Study type
- Prospective, randomized, observer-masked, placebo-controlled study
- Sample size
- Five healthy dogs
- Drug
- Topical 0.002% omidenepag isopropyl
- Main finding
- Lowered intraocular pressure in clinically normal dogs
- Pupil effect
- Little apparent effect on pupil diameter
- Population studied
- Clinically normal dogs
- Pilot phase
- Included short-term pressure and ocular irritation assessment
- Human approval
- Approved in the U.S. as Omlonti for open-angle glaucoma or ocular hypertension
A new study in Veterinary Ophthalmology reports that topical 0.002% omidenepag isopropyl reduced intraocular pressure in clinically normal dogs while having little apparent effect on pupil diameter, offering an early look at how this human glaucoma drug might behave in canine eyes. The study, by Hikaru Tsujimura, Tomoaki Kameda, and Kazuya Oikawa, used a prospective, randomized, observer-masked, placebo-controlled design in five healthy dogs following a pilot assessment of short-term pressure effects and ocular irritation.
That matters because omidenepag isopropyl represents a different pharmacologic route from the prostaglandin analogs more familiar in veterinary ophthalmology. In people, the drug is approved in the U.S. as Omlonti for reducing elevated intraocular pressure in open-angle glaucoma or ocular hypertension, and its label describes it as a relatively selective prostaglandin E2 EP2 receptor agonist. Reviews of the human literature describe intraocular pressure reductions in the roughly 20% to 35% range with once-daily use, alongside adverse effects that can include conjunctival hyperemia and concerns in some lens-status subgroups. (dailymed.nlm.nih.gov)
The canine paper is preliminary, but it arrives as interest grows in whether EP2 agonists could broaden the veterinary glaucoma toolkit. The source abstract indicates the investigators measured intraocular pressure and pupil diameter after topical dosing and found pressure-lowering activity without a major pupil effect in normal dogs. That profile would differ from latanoprost’s well-known miotic effect in dogs, which can be clinically useful in some situations but may also shape tolerability and case selection. Prior canine work with latanoprost and latanoprostene bunod has underscored how strongly pupil size and pressure responses can vary by drug and species. (onlinelibrary.wiley.com)
Outside dogs, early veterinary evidence is starting to point in the same direction. A recent feline pilot study in Veterinary Ophthalmology found that omidenepag-treated normal cat eyes had significantly lower intraocular pressure than controls, while pupil diameter changes were not significant. Another cat study reported pressure lowering in both normal and glaucomatous cats, again without significant pupil effects or obvious ocular irritation. Taken together, those reports suggest EP2 agonism may have cross-species ophthalmic potential, but the evidence base is still thin and centered on small pilot datasets. (onlinelibrary.wiley.com)
I didn’t find a standalone press release or broad veterinary industry reaction tied specifically to the dog paper. The most relevant expert context comes from ophthalmology reviews and prescribing information, which frame omidenepag as a mechanistically distinct pressure-lowering agent that may be useful where FP-receptor drugs are insufficient or poorly tolerated. Human reviews also note that, unlike classic prostaglandin F analogs, omidenepag does not appear to produce the same degree of eyelash changes or periorbital fat atrophy in the short term, although conjunctival hyperemia remains common. That’s human experience, not a veterinary safety conclusion, but it helps explain why the molecule is attracting attention. (doi.org)
Why it matters: For veterinary professionals, this study is less about immediate prescribing change and more about pipeline intelligence. Canine glaucoma remains difficult to control long term, and many currently used topical agents come with limitations in efficacy, duration, or case-specific suitability. A drug that lowers intraocular pressure through EP2 signaling, without relying on the same receptor pathway as latanoprost, could eventually offer another option for adjunctive therapy or for dogs that don’t respond as expected to standard topical regimens. But the gap between “works in normal eyes” and “improves outcomes in clinical glaucoma” is substantial, especially in a five-dog study. (onlinelibrary.wiley.com)
There are also practical questions ahead. Omidenepag is a human-labeled product, so veterinary use would be extralabel, and clinicians would need more data on dosing intervals, onset and duration of effect, adverse events, compatibility with other glaucoma medications, and performance in primary versus secondary glaucoma. Because canine glaucoma cases often present with inflammation, buphthalmos, lens instability, or advanced angle disease, normal-dog pharmacodynamics may not translate cleanly to real-world patients. The human label and reviews also point to safety nuances that would need careful species-specific evaluation before broader adoption. (dailymed.nlm.nih.gov)
What to watch: Watch for a full publication with complete numeric results, then for follow-up studies in dogs with naturally occurring glaucoma comparing omidenepag against standard agents, alone and in combination, with enough follow-up to assess both pressure control and ocular tolerability. (onlinelibrary.wiley.com)