Objective: To develop an accurate, precise and linear Reverse Phase High Performance Liquid Chromatographic (RP-HPLC) method for simultaneous quantitative estimation of Metronidazole and Nalidixic acid in tablets and validate as per ICH guidelines.Methods: The optimized method uses a reverse phase C18 column Inertsil ODS C18 column (250X4.6 mm×5µ) mobile phase consisting of mixed phosphate buffer (pH 4.5; KH2PO4+K2HPO4):methanol: acetonitrile in the proportion of 30:50:20 v/v. The mobile phase was set at a flow rate of 1.2 ml/min and the volume injected was 20μl for every injection. The detection wavelength was set at 271 nm. Results: The developed method resulted in Metronidazole eluting at 2.92 min and Nalidixic acid at 3.99 min. Metronidazole exhibited linearity in the range 30-70μg/ml, while Nalidixic acid exhibited linearity in the range 45-105μg/ml. The precision is exemplified by relative standard deviations of 0.714% for Metronidazole and 0.398% for Nalidixic acid. Percentage Mean recoveries were found to be in the range of 98â€102, during accuracy studies. The limit of detection (LOD) for Metronidazole and Nalidixic acid were found to be 2.48µg/ml and 2.24µg/ml respectively, while limit of quantitiation (LOQ) for Metronidazole and Nalidixic acid were found to be 7.51µg/ml and 6.79µg/ml respectively.Conclusion: A simple, accurate, precise, linear and rapid RP-HPLC method was developed for simultaneous quantitative estimation of Metronidazole and Nalidixic acid in tablets and validated as per ICH guidelines. Hence it can be used for the routine analysis of Metronidazole and Nalidixic acid in tablets in various pharmaceutical industries.Â
