Simultaneous RP-HPLC method for the stress degradation studies of atorvastatin calcium and ezetimibe in multicomponent dosage form

A stability-indicating reversed-phase high performance liquid chromatographic (RPHPLC) method has been developed and validated for simultaneous estimation of atorvastatin calcium and ezetimibe for their multicomponent dosage form. The proposed RP-HPLC method utilizes a 125 mm x 4.6 mm i.d 5 mu m Phenomenex C-18 column at ambient temperature; the optimum mobile phase consists of acetonitrile and 0.4% v/v triethylamine (pH adjusted to 5.5 with ortho-phosphoric acid) in the ratio of 55: 45, v/v respectively, flow rate of 1.0 ml/min. Measurements were made at a wavelength of 231 nm. Multicomponent dosage form was exposed to thermal, photolytic, hydrolytic and oxidative stress. No co eluting, interfering peaks from excipients, impurities were observed for the degradation products and hence the method was found to be specific. The method was linear in the range of 5-25 mu g/ml for atorvastatin calcium and ezetimibe. The mean recoveries were 98.82% and 98.72% for atorvastatin calcium and ezetimibe respectively. The method was validated for linearity, range, precision, accuracy, specificity, selectivity, intermediate precision, ruggedness, robustness, solution stability and suitability.