Simultaneous Analysis of Indapamide and Related Impurities in Sustained-Release Tablets by a Single-Run HPLC-PDA Method

The contents of indapamide and related impurities in generic indapamide sustained-release tablets were simultaneously detected by a single-run high performance liquid chromatography equipped with photodiode array detector (HPLC-PDA) method for the quality control in this paper. The results showed the method had a good selectivity and was validated through linearity, limits of detection and quantification, recovery, and precision. The linear ranges of indapamide, 2-methyl-1-nitroso-2,3-dihydro-1H-indole (impurity A, ImA), 4-chloro-N-(2-methyl-1H-indol-1-yl)-3-sulphamoyl-benzamide (impurity B, ImB) and 4-chloro-3-sulfamoylbenzoic acid (impurity 1, Im1) were 0.028-1.80 μg/mL (R=0.999 95), 0.060-1.20 μg/mL (R=0.999 6), 0.032 4-1.20 μg/mL (R=0.999 85) and 0.060-1.20 μg/mL (R=0.999 7) with detection limits of 0.009 3, 0.012, 0.012 and 0.006 μg/mL, respectively. ImA and Im1 were not detectable in the generic drug. The content of indapamide was 96.7% of the labeled amount with a relative standard deviation (RSD) of 1.30%, and the percentage of ImB relative to the labeled amounts of indapamide was 0.106% with an RSD of 1.82%. The content of other unspecified impurities all met the reference quality standards. The results provided references for the quality control and the quality standard study of generic indapamide sustained-release tablets.