Reversed-Phase Liquid Chromatographic Method for Simultaneous Determination of Metformin and Repaglinide in Pharmaceutical Preparations

A simple, rapid, precise and accurate reversed phase high performance liquid chromatographic method has been developed for the simultaneous determination of metformin in combination with repaglinide. This method uses a Hypersil ODS C₁₈ (250mm×4.6mm×5_&#956 particle Size) analytical column, a mobile phase of acetonitrile and buffer containing 0.05 M ammonium acetate in the ratio 60:40 (v/v), and pH adjusted to 5.0 with orthophosphoric acid. The instrument was set with a flow rate of 1 ml/min and PDA detector wavelength at 271 nm. The retention times for metformin and repaglinide are 3.13 min and 10.01min respectively. The method was validated as per the ICH guidelines. The linearity range for metformin and repaglinide were found to be 200-1200 and 0.5-3.0 μg/ml respectively. The percentage recovery for metformin and repaglinide are in the range between 99.25-99.48 and 98.58-100.26 respectively. The correlation coefficients of metformin and repaglinide were 0.999, and 0.999, respectively. The relative standard deviation for six replicates was always less than 2%. The statistical analysis proves that the method was suitable for analysis of metformin and repaglinide as a bulk drug and in pharmaceutical formulation without any interference from the excipients.