The main objective of this work is to develop a simple, fast, accurate, precise, rugged and linear Reverse Phase High Performance Liquid Chromatographic (RP-HPLC) method for simultaneous quantitative estimation of Duloxetine and Methylcobalamin in capsules and validate as per ICH guidelines. The optimized method uses a reverse phase column, Phenomenex Luna C18 (250 X 4.6 mm;5μ), a mobile phase of triethylammonium phosphate buffer (pH 3.5):acetonitrile in the proportion of 40:60 v/v, flow rate of 0.9ml/min and a detection wavelength of 260 nm using a UV detector. The developed method resulted in Duloxetine eluting at 3.48min and Methylcobalamin at 2.19min, having a run time of 5minutes. Duloxetine exhibited linearity in the range 100-300μg/ml, while Methylcobalamin exhibited linearity in the range 5-15μg/ml. % Relative standard deviations of system, intra day and ruggedness were found to be less than 2 for both the drugs. Percentage Mean recoveries were found to be in the range of 90?¢???110, during accuracy studies by absolute method. A simple, fast, accurate, precise, linear and rugged RP-HPLC method was developed for simultaneous quantitative estimation of Duloxetine and Methylcobalamin in capsules and validated as per ICH guidelines. Hence it can be used for the routine analysis of Duloxetine and Methylcobalamin in capsules in various pharmaceutical industries.
