1,4-Dihydro-2,6-dimethyl-3-(2-cyanoethoxycarbonyl)-5-ethoxycarbonyl-4-(2,3-dichlorophenyl)pyridine-13C4 is an intermediate in the synthesis of Felodipine-13C4, d3 (F232376), the labeled analogue of Felodipine (F232375), a dihydropyridine calcium channel blocker.