Cleaning Method Development and Validation for the Simultaneous Estimation of Olmesartan and Atorvastatin by HPLC

A simple and reproducible, RP-HPLC cleaning validation method for the simultaneous estimation of Olmesartan and Atorvastatin has been developed. The chromatography was carried out on Phenomenex Synergi polar RP-80A column (250mm×4.6mm, 4μm) in an isocratic mode utilizing ammonium acetate buffer (pH 6.5): acetonitrile (65: 35, v/v) as mobile phase, at a flow rate of 1.5mL/min. Detection was carried out at Isosbestic point of 252nm. Retention times of olmesartan and atorvastatin were 3.847±0.2 min and 8.930±0.2 min, respectively. The method was validated as per ICH guidelines. The method was found to be specific as there was no swab interference. The Beer Lambert's law was obeyed in the concentration range 0.1–10μg/mL for both olmesartan and atorvastatin with Correlation Coefficient, r2 = 0.9999. The % RSD of six replicates and mean % recovery were found to be within acceptable limits for both the drugs. The LOD was 0.003μg/ml for olmesartan and atorvastatin and the LOQ was 0.1μg/ml for olmesartan and atorvastatin which showed that method was sensitive. The method was robust as observed from insignificant variation of analysis results by adopting minor changes in chromatographic conditions. Stability studies conducted on mixed standard solution kept on bench top and under refrigeration conditions showed that the solution was stable on benchtop for 2 h, while the refrigerated solution was stable up to 24 h.