Fluprostenol is a metabolically stable analog of PGF2α with potent FP receptor agonist activity. The isopropyl ester of fluprostenol has been approved for use as an ocular hypotensive drug for the treatment of glaucoma and is sold under the Alcon trade name Travoprost. Acting as a prodrug, Fluprostenol isopropyl ester is converted by esterase activity in the cornea to yield the corresponding active free acid, (+)-fluprostenol. Cayman’s Fluprostenol ELISA is a sensitive detection method for measuring the free acid form of fluprostenol. The assay also detects the isopropyl ester form of fluprostenol, but with less sensitivity. The assay has been validated for use in aqueous humor samples.