Abstract

Jagadeesh Narkedimilli^1,2,*, Y. Ravindrakumar¹ ,Sandeep Mohanty¹, T. Srinivasarao¹, A. Jayashree²

DOI : http://dx.doi.org/10.13005/ojc/310363

Diltiazem (DTZ) is an optically active calcium channel blocker having a benzodiazepine structure. Two impurities (referred as DTZ-I and DTZ-II) were detected with area percentages ranging from 0.1% to 0.15% during the impurity profile study of Diltiazem hydrochloride drug substance. A simple isocratic high performance liquid chromatographic method (HPLC) and liquid chromatography–mass spectrometry (LC–MS) were used for the detection. The impurities were isolated by preparative column chromatography. Analytical information from nuclear magnetic resonance and mass spectral data of the potential impurities revealed their structures as 2-(4-methoxyphenyl)-5-methyl-4-oxo-2,3,4,5-tetrahydrobenzo[b][1,4]thiazepin-3-yl acetate (DTZ-I) and 2-(4-methoxyphenyl)-4-oxo-5-vinyl-2,3,4,5-tetrahydrobenzo[b][1,4]thiazepin-3-yl acetate (DTZ-II). Impurity identification, isolation and structure elucidation were discussed.

Diltiazem; Potential impurities; Isolation; characterization techniques

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