Novel and Validated Stability-Indicating HPLC Method for Simultaneous Estimation of Olmisartan and Chlorthalidone in Oral Solid Form

A simple, rapid, accurate, precise and economical reverse phase high performance liquid chromatographic method was developed for simultaneous quantification of two anti-hypertensive drugs Olmesartan and Chlorthalidone. The separation of both the drugs was achieved on BDS C18 250mm x 4.6 mm, 5m using a mobile phase of 10 mM orthophosphoric acid buffer and acetonitrile (45:55v/v) at a flow rate of 1.0 mL min-1 and detection was performed at 212 nm using photodiode array (PDA) detector. The drug was subjected to various ICH prescribed stress conditions including hydrolysis (neutral, acid and alkaline), oxidation, photolysis and thermal degradation. The proposed method was validated with respect to specificity, linearity, accuracy, and precision, limit of detection (LOD), limit of quantitation (LOQ), stability and robustness as per ICH guidelines. The proposed analytical method could effectively separate the drug from its degradation products employed as stability indicating studies.