Celecoxib EP Impurity A

Celecoxib EP Impurity A is a fluorinated pyrazole sulfonamide derivative characterized by a 4-fluorophenyl-substituted pyrazole core linked to a benzenesulfonamide moiety. The structure features a 3-methyl-1H-pyrazol-5-yl group bridging the fluorinated phenyl and sulfonamide functionalities, differing from Celecoxib by the absence of a trifluoromethyl substituent and the presence of a 4-fluoro substitution on the aryl ring. This impurity arises during synthetic pathways involving nucleophilic aromatic substitution. It serves as an HPLC reference standard for quantifying process-related impurities in Celecoxib drug substance analysis.