Pharmacologic Characterization of Omidenepag Isopropyl, a Novel Selective EP2 Receptor Agonist, as an Ocular Hypotensive Agent

Purpose: The objective of this study was to investigate the pharmacologic characteristics of omidenepag isopropyl (OMDI), a compound developed as a novel intraocular pressure (IOP)-lowering agent, with better IOP control and fewer side effects than other prostanoid receptor agonists such as prostaglandin F receptor (FP) agonists.

Methods: Binding activities of OMDI and its hydrolyzed form, omidenepag (OMD), to human recombinant prostanoid receptors (DP1-2, EP1-4, FP, and IP) were evaluated. Based on these binding assays, the agonistic activities of OMDI and OMD were further evaluated using cultured cells expressing selected prostanoid receptors. The pharmacokinetics of OMDI after topical administration was assessed in rabbits by measurement of the concentrations of both OMDI and OMD in aqueous humor. The ocular hypotensive effect of OMDI was evaluated in ocular normotensive rabbits, dogs, and both ocular normotensive and hypertensive monkeys.

Results: OMD was determined to be a selective EP2 receptor agonist. OMDI weakly bound to EP1; however, the agonistic activity of OMDI to this receptor was not demonstrated in the functional assay. After topical administration of OMDI, OMD was detected in aqueous humor whereas OMDI was not detectable. OMDI significantly lowered IOP in both ocular normotensive and hypertensive Animals. The significant ocular hypotensive effects of OMDI were demonstrated by both single and repeated dosing, and its effective duration suggests sufficient efficacy by once-daily dosing.

Conclusions: These studies demonstrated that OMDI is hydrolyzed in the eye to OMD, an EP2 receptor agonist, with a significant ocular hypotensive effect in both ocular normotensive and hypertensive animal models.