Structural Elucidation of Novel Degradation Impurity and Development, Validation of a Single HPLC Method for all Putative Impurities of Clobetasol Propionate in a Foam Drug Product

Abstract Clobetasol Propionate is a highly strong corticosteroid that is used in a variety of topical medication formulations, including foam, ointment, lotion, spray and shampoo; with a dosage strength of 0.05% (w/w). The goal of this research was to identify and characterize a substantial unknown impurity (UK) detected during the stability testing of a Clobetasol Propionate foam pharmaceutical product in accelerated conditions (40°C and 75% relative humidity). Developing a single, robust and accurate HPLC method that is LC–MS compatible for quantifying all 14 potential Clobetasol Propionate impurities in therapeutic drugs is another goal. Preparative column chromatography was used to separate the impurity, and spectroscopic techniques like IR, NMR and MS were used to characterize its structure. The structure of isolated UK was effectively characterized and defined using spectroscopic data evaluation. The chromatographic method has also been validated according to the International Conference on Hominization's Q (2) quality guidelines. The isolated and characterized impurity had the same equivalence as the impurity found during stability testing. Precision, accuracy, linearity, robustness and ruggedness are all met in the method validation data.