(11β)-9-Fluoro-11-hydroxy-16-methyl-3-oxo-androsta-1,4,16-triene-17-carboxylic Acid is one of Clobetasol propionate impurities. Clobetasol propionate is a glucocorticoid that induces monooxygenase activity in vivo. It alters the structure of tight junctions in epidermis and smoothened hedgehog pathway receptor agonist. It can be used as an anti-inflammatory, immunosuppressive and antimitotic agent. Active in vivo.