Stability-indicating HPLC-DAD Method for Simultaneous Determination of Atorvastatin, Irbesartan, and Amlodipine in Bulk and Pharmaceutical Preparations

The present study describes a convenient stability-indicating HPLC-DAD method for the separation and simultaneous determination of the drugs atorvastatin, irbesartan, and amlodipine in bulk and formulations. The method proposed demonstrated good separation between atorvastatin, irbesartan, amlodipine and their main degradation products. Separation was executed on a Waters XBrigde C18 column (5 mu m, 25 x 0.46cm) using a gradient mobile phase system consisting of acetonitrile and orthophosphoric acid buffer (pH 2.2) at a flow rate of 1mL/min and UV detection at 240nm. The drugs were subjected to acidic and basic hydrolysis, oxidation, exposure to UV light, and exposure to temperature (dry heat) to apply stress conditions. Linearity of the method was evaluated in the range 5-30 mu g/mL for each drug with correlation coefficient values (r(2)) of 0.9982, 0.9973, and 0.9986 for atorvastatin, irbesartan, and amlodipine, respectively. The limits of detection were 0.05, 0.06, and 0.08 mu g/mL for the three compounds, respectively. No interference was observed with the detection of the compounds in presence of degradable products; hence, it is confirmed that the analysis is stability-indicating.