A simple and precise stability indicating RP-HPLC method was developed and validated for simultaneous determination of Metoprolol succinate and Chlorthalidone in bulk and combined tablet formulation. Chromatography was carried out on Inertsil ODS C18 (250 x 4.6 mm, 5m particle size) column in an isocratic mode with mobile phase containing phosphate buffer (adjusted to pH 5.5 with dilute othophosphoric acid and acetonitrile in the ratio of 55:45% v/v at a flow rate of 0.8 ml/min. The analyte was monitored using PDA detector at 219 nm. The retention time was found to be 3.763 min and 4.924 min for Metoprolol succinate and Chlorthalidone respectively. The proposed RP-HPLC method was found to be having linearity in the concentration range of 12.5-75 μg/ml for Metoprolol succinate and 3.125-18.75 μg/ml for Chlorthalidone with correlation coefficient value of 0.999 respectively. The mean % recoveries obtained were found to be 99.32-99.98 % for Metoprolol succinate and 99.52-99.84 % for Chlorthalidone respectively. Stress testing which covered acid, base, peroxide, UV light, neutral and thermal degradation was performed on under test to prove the specificity of the method and the degradation was achieved. The developed method has been statistically validated according to ICH guide lines. Thus the proposed method can be successfully applied for the stability indicating simultaneous determination of Metoprolol succinate and Chlorthalidone in bulk and combined tablet dosage form and in routine quality control analysis.
