Bimatoprost is an F-series prostaglandin (PG) analog which has been approved for use as an ocular hypotensive drug. Oxidation of the C-15 hydroxyl group and amide hydrolysis of Bimatoprost produces 15-keto-17-phenyl trinor PGF2α. 15-keto-17-phenyl trinor PGF2α is a potential metabolite of bimatoprost when administered to animals. 15-keto PG analogs are potential minor impurities in commercial preparations of their corresponding bulk drug compounds. Although much less potent that the parent compound, 15-keto PGs still retain the ability to produce a small but measurable decrease (1 mm Hg) in the intraocular pressure of normal cynomolgus monkeys when administered at a dose of 1 μg eye. 15-keto Latanoprost (15-keto-17-phenyl-13,14-dihydro trinor PGF2α isopropylester) is a miotic in the normal cat eye, causing an 8 mm reduction in pupillary diameter at 5 μg eye. Again, this is not as potent as many other F-type PGs; for example, PGF2α will produce this degree of miosis at a dose of less than 1 μg eye.
17-phenyl trinor PGF2α N-ethyl amide is an F-series prostaglandin analog which has been approved for use as an ocular hypotensive drug, sold under the Allergan trade name Bimatoprost. The N-ethyl amide prostaglandin prodrugs are converted to the active free acid more slowly than the analogous prostaglandin ester prodrugs such as latanoprost. This product is the isopropylester of the free acid prostaglandin which corresponds to Bimatoprost. The free acid, 17-phenyl trinor PGF2α, is a potent FP receptor agonist. In human and animal models of glaucoma, FP receptor agonist activity corresponds very closely with intraocular hypotensive activity. The 17-phenyl trinor PGF2α isopropylester derivative was examined for IOP-lowering activity during the development of latanoprost. At the dose of 3 μg eye in the monkey, 17-phenyl trinor PGF2α isopropylester was the most potent analog tested in reducing IOP, lowering the IOP 1.3 mm Hg below the level achieved by latanoprost. However, this derivative was also significantly more irritating to the eye than latanoprost.