Publications (2)5.42 Total impact
- [Show abstract] [Hide abstract]
ABSTRACT: Better control of intraocular pressure (IOP) is the most effective way to preserve visual field function in glaucomatous patients. While prostaglandin FP analogs are leading the therapeutic intervention for glaucoma, new target classes also are being identified with new lead compounds being developed for IOP reduction. One target class currently being investigated includes the prostaglandin EP receptor agonists. Recently PF-04217329 (Taprenepag isopropyl), a prodrug of CP-544326 (active acid metabolite), a potent and selective EP(2) receptor agonist, was successfully evaluated for its ocular hypotensive activity in a clinical study involving patients with primary open angle glaucoma. In the current manuscript, the preclinical attributes of CP-544326 and PF-0421329 have been described. CP-544326 was found to be a potent and selective EP(2) agonist (IC(50) = 10 nM; EC(50) = 2.8 nM) whose corneal permeability and ocular bioavailability were significantly increased when the compound was dosed as the isopropyl ester prodrug, PF-04217329. Topical ocular dosing of PF-04217329 was well tolerated in preclinical species and caused an elevation of cAMP in aqueous humor/iris-ciliary body indicative of in vivo EP(2) target receptor activation. Topical ocular dosing of PF-04217329 resulted in ocular exposure of CP-544326 at levels greater than the EC(50) for the EP(2) receptor. PF-04217329 when dosed once daily caused between 30 and 50% IOP reduction in single day studies in normotensive Dutch-belted rabbits, normotensive dogs, and laser-induced ocular hypertensive cynomolgus monkeys and 20-40% IOP reduction in multiple day studies compared to vehicle-dosed eyes. IOP reduction was sustained from 6 h through 24 h following a single topical dose. In conclusion, preclinical data generated thus far appear to support the clinical development of PF-04217329 as a novel compound for the treatment of glaucoma.
- [Show abstract] [Hide abstract]
ABSTRACT: Prostaglandins are widely used to lower intraocular pressure (IOP) as part of the treatment regimen for glaucoma. While FP and EP2 agonists are known to lower IOP, we investigated the ocular hypotensive activity and ocular drug distribution of PF-04475270, a novel EP4 agonist following topical administration in normotensive Beagle dogs. PF-04475270 is a prodrug of CP-734432, which stimulated cAMP formation in HEK293 cells expressing EP4 receptor and beta-lactamase activity in human EP4 expressing CHO cells transfected with a cAMP response element (CRE) with an EC(50) of 1 nM. Prodrug conversion and transcorneal permeability were assessed in rabbit corneal homogenates and a human corneal epithelial cell (cHCE) model. The compound underwent rapid hydrolysis to CP-734432 in corneal homogenates, and exhibited good permeability in the cHCE model. The descending order of ocular exposure to CP-734432 after topical dosing of PF-04475270 in dogs was as follows: cornea > aqueous humor >or= iris/ciliary body. When administered q.d., PF-04475270 lowered IOP effectively in the dog IOP model both after single and multiple days of dosing. A maximum decrease in IOP with PF-04475270 was between 30 and 45% at 24h post-dose relative to that observed with vehicle. In conclusion, PF-04475270 is a novel ocular hypotensive compound which is bioavailable following topical dosing, effectively lowering IOP in dogs. EP4 agonists could be considered as potential targets for lowering IOP for the treatment of glaucoma and ocular hypertension.