Azelnidipine Methoxy impurity

Azelnidipine Methoxy impurity is a dihydropyridine-based calcium channel blocker derivative featuring a 2-methoxyethyl substituent on the pyridine ring and a 4-(4-chlorophenyl)-1,4-dihydropyridine core. This impurity arises from methylation of a hydroxyl group present in a synthetic intermediate, resulting in a methoxy group replacing a hydrogen atom at the 3-position of the dihydropyridine ring. The compound exhibits structural similarity to the parent drug, differing primarily in the electron-donating methoxy substitution, which alters its metabolic stability and chromatographic retention. It serves as an HPLC reference standard for quantifying process-related impurities in Azelnidipine active pharmaceutical ingredient batches.