High-performance liquid chromatography method for assay of diltiazem hydrochloride and its related compounds in bulk drug and finished tablets

Article abstract of DOI:10.1002/jps.2600780315

The method provides for the resolution of trans-diltiazem and seven known and several unknown related compounds from diltiazem HCl. Minimum detectable amounts were < 0.1%, except for an intermediate which originates early in the synthetic process, for which the sensitivity is ~2%. The relative standard deviation of the assay procedure is 0.15%. Total related compounds in four bulk drugs and four tablet samples were < 0.25%. The specific rotation of four samples of diltiazem HCl analyzed in duplicate was between +112 and +114°. The UV absorption spectra of all compounds exhibited two maxima, one between 203 and 213 nm and the other between 230 and 244 nm.