parecoxib meta isomer

Parecoxib meta isomer is a positional isomer of the parent NSAID prodrug parecoxib, characterized by a meta-substituted aryl sulfonamide moiety relative to the pyrazole ring. Its structure incorporates a 4-pyridyl ester linked to a meta-oriented phenylsulfonamide group, differing from the para configuration in the parent compound. The molecule retains the core 2-propylpyrazole framework but exhibits altered steric and electronic properties due to the meta substitution. This isomer arises as a synthetic byproduct during API manufacturing via divergent sulfonamide coupling pathways. It serves as an HPLC reference standard for impurity profiling in parecoxib formulations.