Identification and synthesis of new process impurities of amlodipine, a calcium channel blocker

Amlodipine belongs to the class of calcium channel blocker that is used to reduce high blood pressure (hypertension). Two related substances of amlodipine namely 3-(2-[1.3-dioxo-1,3-dihydro-2H-isoindol-2-yl]ethyl)-5-methyl-(4RS)-4(2-chlorophenyl)-2-([2-(1,3-dioxo-1,3-dihydro-2H-isoin-dol-2-yl)ethoxy]methyl)-6-methyl-1,4-dihydropyridine-3,5-dicarboxylate (11) and 3-([2-aminoethyl]-5-aminoethoxy)-4-(2-chlorophenyl)-1,4-dihydro-6-methylpyridine-3,5-dicarboxylate (12) were identified. The present work describes the origin, synthesis, and characterization of these related substances.