Animal experiment:

Three year-old, male cynomolgus monkeys with body weights ranging from 2.6 to 5.0 kg are used in this study. Animals are dosed twice daily for 28 days in the right eye with Taprenepag isopropyl (0.75, 12, or 36 mg/day), and an equal volume of vehicle (containing cremophor, boric acid, BAC, and EDTA) is dosed in the left eye. An additional 2 monkeys are included in the high-dose group to assess recovery over a 28 day period. Toxicity outcomes are based on the assessment of clinical signs, body weight, ophthalmic examination, pupillary diameter, corneal staining, pachymetry, and noncontact specular microscopy. IOP is measured once during the predose phase and before dosing on Days 1, 8, 15, 22, and 29 of the dosing phase, then once during each week of the recovery period[1].

Taprenepag isopropyl is a highly selective EP2 receptor agonist.

Taprenepag isopropyl is a highly selective EP2 receptor agonist. Intraocular pressure (IOP) in the left, vehicle-dosed eye typically remains within the normal range. In the right (Taprenepag isopropyl-dosed) eye, IOP is reduced in all dose groups. In the high-dose group, IOP is reduced to the extent that it cannot be measured (<4mm Hg) on Days 22 and 29. There are no clinical signs or changes in body weight observed with any dose of Taprenepag isopropyl administration, and noocular findings occur for animals in the low-dose group (0.75 mg/day)[1].

[1]. Yanochko GM, et al. Investigation of ocular events associated with taprenepag isopropyl, a topical EP2 agonist in development for treatment of glaucoma. J Ocul Pharmacol Ther. 2014 Jun;30(5):429-39.