Bimatoprost is an F-series prostaglandin (PG) analog 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, a potential metabolite when administered to animals. 15-keto PG analogs can be minor impurities in commercial preparations of corresponding bulk drug compounds. Although much less potent than the parent compound, 15-keto PGs can still produce a small but measurable decrease (1 mm Hg) in intraocular pressure of normal cynomolgus monkeys at a dose of 1 μg/eye. 15-keto Latanoprost (15-keto-17-phenyl-13,14-dihydro trinor PGF2α isopropyl ester) acts as a miotic in normal cat eyes, causing an 8 mm reduction in pupillary diameter at 5 μg/eye. This is less potent compared to many other F-type PGs; for example, PGF2α induces similar miosis at less than 1 μg/eye.