Halobetasol Propionate

Halobetasol Propionate is a corticosteroid derivative featuring a 11β-hydroxyl group esterified with propionic acid, substituted by a 6α-chloro and 9-fluoro moiety. This compound arises as a synthetic byproduct during the esterification of Halobetasol's parent hydroxyl group, introducing a propanoyl chain that modulates its lipophilicity. Structurally, it retains the core tetrahydrocyclopentanophenanthrene skeleton with a Δ1-deficiency and a 16α-methyl group, distinguishing it from the parent drug. It serves as an HPLC reference standard for quantifying esterification-related impurities in Halobetasol formulations.