Celecoxib EP Impurity B

Celecoxib EP Impurity B is a process-related byproduct derived from the synthetic pathway of Celecoxib, featuring a pyrazole ring substituted with trifluoromethyl and sulfonamide functionalities. Its structure retains the core aromatic sulfonamide scaffold but exhibits a regioisomeric shift in the pyrazole-benzene coupling relative to the parent drug, introducing altered steric and electronic properties. The compound incorporates fluorinated aromatic moieties and a methylated phenyl ring, conferring distinct H-bonding and solubility characteristics. This impurity arises from a side reaction during pyrazole ring formation, leading to positional isomerism. It functions as an HPLC reference standard for monitoring synthetic process consistency in Celecoxib drug substance analysis.