Synonyms: Betamethasone 11,21-Diacetate, Betamethasone Acetate Imp. C (EP), Pregna-1,4-diene-3,20-dione, 11,21-bis(acetyloxy)-9-fluoro-17-hydroxy-16-methyl-, (11β,16β)-, (11β,16β)-11,21-Bis(acetyloxy)-9-fluoro-17-hydroxy-16-methylpregna-1,4-diene-3,20-dione