Diltiazem USP Related Compound B , (2S,3S)-2-(4-methoxyphenyl)-4-oxo-2,3,4,5-tetrahydro-1,5-benzothiazepin-3-ylacetate, (2S-cis)-3-(Acetyloxy)-2,3-dihydro-2-(4-methoxyphenyl)-1,5-Benzothiazepin-4(5H)- one, Acetoxy Lactam Diltiazem, (2S-cis)-3-(Acetyloxy)-2,3-dihydro-2-(4-methoxyphenyl)-1,5-Benzothiazepin-4(5H)-one