Megestrol acetate Impurity I

Megestrol acetate Impurity I is a steroidal derivative arising from partial hydrolysis of the 17β-acetoxy group in megestrol acetate, resulting in a free 17β-hydroxyl moiety. The compound retains the 3-keto, 4-en-17α-pregnane core with a 11β-methyl group and 17β-hydroxyl functionality, distinguishing it from the fully acetylated parent drug. This impurity forms via ester cleavage under acidic or hydrolytic conditions during synthesis or storage. Its primary application is as an HPLC reference standard for quantifying process-related degradation in megestrol acetate formulations.