azelnidipine methyl imp

Azelnidipine methyl impurity is a synthetic byproduct arising from methylation at the pyridine nitrogen of the parent dihydropyridine scaffold. It retains the 1,4-dihydropyridine core and α-methylbenzyl substituent but features a methylamino group in place of the primary amine, altering its lipophilicity and H-bonding capacity. This structural modification reduces calcium channel antagonist activity while enhancing chromatographic retention. Used as an HPLC reference standard for quantifying process-related impurities in azelnidipine drug substance.