title: Identification and characterization of three impurities in clocortolone pivalate.
abstract: Clocortolone pivalate is a synthetic corticosteroid that can be used to cure corticosteroid-responsive dermatoses. Three previously unknown impurities detected by HPLC were isolated by semi-preparative LC. Based on the NMR and MS spectral data, these were identified as (6R,9R,16R)-9-chloro-6β-fluoro-11β,21-dihydroxy-16α-methylpregna-1,4-diene-3,20-dione-21-pivalate (Impurity I), (9R,16R)-9-chloro-4-fluoro-11β,21-dihydroxy-16α-methylpregna-1,4-diene-3,20-dione-21-pivalate (Impurity II) and (9R,16R)-9-chloro-6α-fluoro-11β,21-dihydroxy-16α-methylpregna-1,4-diene-3,20-dione-11,21-dipivalate (Impurity III). The possible mechanism of the formation of the impurities is discussed.
authors.affiliation: School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang 110016, People's Republic of China.
authors.forename: Weizhuo
authors.initials: W
authors.lastname: Xu
authors.forename: Xian
authors.initials: X
authors.lastname: Jia
authors.forename: Wenbao
authors.initials: W
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Yinan
authors.initials: Y
authors.lastname: Chen
authors.forename: Lina
authors.initials: L
authors.lastname: Zhou
authors.forename: Song
authors.initials: S
authors.lastname: You
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005448:Fluocortolone / Q000031:analogs & derivatives* / Q000737:chemistry; D005938:Glucocorticoids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D005938:Glucocorticoids; D005448:Fluocortolone; C007088:clocortolone pivalate