azelnidipine Methoxy imp

Azelnidipine Methoxy imp is a process-derived impurity characterized by a methoxy substitution on the 4-position of the 3-nitrophenyl ring of the parent dihydropyridine calcium channel blocker. This derivative retains the core 1,4-dihydropyridine scaffold and 3,5-dimethylpyrazole linkage but features an additional methoxy group conjugated to the nitroaromatic moiety, altering electronic distribution and metabolic stability. The compound arises during synthetic pathways involving nucleophilic aromatic substitution of the nitro group precursor. This impurity serves as a critical HPLC reference standard for quantifying process-related methylation byproducts in azelnidipine active pharmaceutical ingredient batches.