Determination of eprosartan mesylate and hydrochlorothiazide in tablets by derivative spectrophotometric and high-performance liquid chromatographic methods.

Two new simple and selective assay methods have been presented for the analysis of eprosartan mesylate (EPR) and hydrochlorothiazide (HCT) in pharmaceutical formulations. The first method is based on first-derivative ultraviolet spectrophotometry with zero-crossing measurements at 246 and 279 nm for EPR and HCT, respectively. The assay was linear over the concentration ranges 3.0-14.0 µg/mL for EPR and 1.0-12.0 µg/mL for HCT. The quantification limits for EPR and HCT were found to be 1.148 and 0.581 µg/mL, respectively, while the detection limits were 0.344 µg/mL for EPR and 0.175 µg/mL for HCT. The second method involved isocratic reversed-phase liquid chromatography using a mobile phase composed of acetonitrile-10 mM phosphoric acid (pH 2.5) (40:60, v/v). Olmesartan was used as internal standard and the substances were detected at 272 nm. The linearity ranges were found to be 0.5-30 and 0.3-15.0 µg/mL for EPR and HCT, respectively. The limits of detection were found to be 0.121 µg/mL for EPR and 0.045 µg/mL for HCT. The limits of quantification were found to be 0.405 and 0.148 µg/mL for EPR and HCT, respectively. The proposed methods were successfully applied to the determination of commercially available tablets with a high percentage of recovery and good accuracy and precision.