Validation of liquid chromatographic method for assay of chlorthalidone in tablet formulations.

A stability-indicating, reverse phase liquid chromatographic (LC) method was developed for assay of chlorthalidone in tablet formulations. The chromatographic system separates the parent compound from its potential hydrolysis product (4'-chloro-3'-sulfamoyl-2-benzophenone carboxylic acid), which can be quantitated at low levels, and another degradation product (2-chloro-5-(1-methoxy-3-oxo-1-isoindolinyl)benzenesulfonamide), which was found during the experimental work. The procedure can also be used for content uniformity determinations. The general utility of the method was demonstrated by the assay of several product brands. The validated procedure was shown to be accurate, precise, reproducible, and specific.