Nisoldipine Impurity-II

Nisoldipine Impurity-II is a dihydropyridine derivative arising from the oxidative degradation of the parent compound, characterized by a 1,4-dihydropyridine core substituted with a 2-nitrophenyl group at the 4-position and a methyl ester at the 3-position. The impurity exhibits a structural isomerism at the double bond configuration (E/Z) relative to nisoldipine, altering its conformational flexibility. This compound serves as a critical HPLC reference standard for quantifying degradation pathways in stability studies of nisoldipine formulations.