15(R)-15-methyl PGF2α methyl ester is a lipid soluble prodrug form of 15(R)-15-methyl PGF2α with increased membrane permeability. Acid-catalyzed epimerization of 15(R)-15-methyl PGF2α methyl ester and hydrolysis of the ester converts it into the active 15(S)-15-methyl PGF2α.{4631,1989}