Diltiazem EP Impurity A

Chemical Name: Diltiazem USP RC A ;  Diltiazem (2R)-Isomer ; (2R,3S)-5-[2-(Dimethylamino)ethyl]-2-(4-methoxyphenyl)-4-oxo-2,3,4,5-tetrahydro-1,5-benzothiazepin-3-yl acetate ;