Development and validation of a stability-indicating RP-HPLC for the simultaneous determination of Atorvastatin Calcium and Simvastatin in pharmaceutical solid dosage forms

Abstract

A reverse phase high performance liquid chromatographic (RP-HPLC) method was suitable for simultaneous determination of AT, ST and their degradation products in raw materials and pharmaceuticals formulations has been developed. The separation was accomplished on X-Bridge shield RP₁₈ (50mm × 4.6mm, 3.5µm) column under isocratic mode. The mobile phase consisting of 0.02M ammonium acetate buffer with pH 4.0 and organic modifier mixture (acetonitrile-THF, 95:5) in the ratio of 50:50, v/v respectively. The flow rate was monitored at 0.8mL/min, with 5µL injection volume and a PDA detector set at 246nm used for detection. Forced degradation of AT and ST were carried out under thermal, acidic, alkaline, peroxide, sunlight and ultraviolet light conditions. Under stressed conditions AT and ST were degraded and the mass balance was found to be above 95%. The retention times of AT and ST were 2.5min and 10.5min, respectively. The total run time was 15min within which from the drug product and degradation processes. The linearity was established for atorvastatin calcium and simvastatin in the concentration range of 50% to 150% of target concentration and correlation found to be 0.999. A RP-HPLC method has been validated for specificity, precision, linearity, accuracy, ruggedness and robustness. The proposed analytical method demonstrated to be suitable for quantitation of all relevant degradants, as well as respective drug products.