Quantitation of Hydrochlorothiazide in Combination with Methyldopa and Propranolol Hydrochloride by High-Performance Liquid Chromatography

A stability indicating assay method based on highperformance liquid chromatography has been developed for the quantitation of hydrochlorothiazide in combination with methyldopa and propranolol hydrochloride. The method is accurate, reproducible and precise with an average percent relative standard deviation of 1.3. The method can also be used for the quantitation of the only known impurity/decomposition product (4-amino, 6 chloro, 1,3 benzenedisulfonamide) in hydrochlorothiazide. For the complete separation of methyldopa from hydrochlorothiazide, a counterion, 1-heptanesulfonic acid sodium was added to the mobile phase to increase the retention time of methyldopa. A 4-5 minutes time to extract hydrochlorothiazide from tablets appears to be satisfactory.