17-phenyltrinorProstaglandinF2α N-ethyl amide (17-phenyltrinor PGF2α) is an F-series prostaglandin analog which has been approved for use as an ocular hypotensive drug, sold under the Allergan trade name 17-phenyltrinor PGF2α ethyl amide. Investigations in our lab have shown that 17-phenyltrinor PGF2α ethyl amide is converted by an amidase enzymatic activity in the human cornea to yield the corresponding free acid, with a conversion rate of about 25 μg cornea 24 hours. The free acid, 17-phenyltrinor PGF2α, is a potent FP receptor agonist. 15(R)-17-phenyltrinor PGF2α is the 15-epi, or unnatural isomer of this active free acid metabolite. It has much diminished FP receptor-mediated activity
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-phenyltrinor PGF2α. 15-keto-17-phenyltrinor 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 isopropyl ester) 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.
N-Desethyl Bimatoprost (17-phenyltrinor PGF2α amide) is an F-series PG analog in which the C-1 carboxyl group has been modified to an unsubstituted amide. PG esters have been shown to have ocular hypotensive activity. PG N-ethyl amides were recently introduced as alternative PG hypotensive prodrugs. Although it has been claimed that PG amides are not converted to the free acids in vivo, studies have shown that bovine and human corneal tissue converts the amides of various PGs to the free acids with a conversion efficiency of about 10-20% relative to the hydrolysis of isopropyl esters. 17-phenyltrinor PGF2α amide would be expected to show the typical intraocular effects of latanoprost, but with the much slower hydrolysis pharmacokinetics of the PG N-amides.