15(R)-15-methylPGF2α, a metabolically stable analog of PGF2α, is an inactive, prodrug PGF agonist intended for activation by gastric acid through oral administration. This transformation involves acid-catalyzed epimerization that converts 15(R)-15-methylPGF2α into its active counterpart, the 15(S)-isomer. Upon conversion, the 15(S)-isomer has been shown to induce luteolysis in rhesus monkeys following an approximately 12 mg/animal dosage, a response not observed with the 15(R)-isomer.