Azelnidipine B form

Azelnidipine B form is a dihydropyridine-based impurity arising from the synthetic pathway of the parent calcium channel blocker azelnidipine. It retains the 1,4-dihydropyridine core but lacks the methyl substituent at the 5-position, featuring instead a hydrogen atom and a partially oxidized pyridine ring with a hydroxyl group at the 2-position. This structural deviation disrupts the parent compound's conformational flexibility, reducing its pharmacological activity. The compound serves as a critical HPLC reference standard for quantifying process-related impurities in azelnidipine formulations.