RP-HPLC Method for the Simultaneous Estimation of Amoxicillin Trihydrate and Metronidazole in the Combined Dosage Form

A simple, rapid and selective RP -HPLC method has been developed for determination of Amoxicillin trihydrate and Metronidazole in the pharmaceutical dosage form. The chromatographic separation was achieved with reverse phase Column in isocratic mode and mobile phase containing 0.1N Potassium dihydrogen phosphate (adjusted to pH 4.5 by Orthophosphoric acid) and Methanol in the ratio of 50:50 % v/v was used. The flow rate was 0.6 mL/min and effluent was monitored at 235 nm. Retention time was found to be 6.1 min for Amoxicillin trihydrate and 7.9 min for Metronidazole, respectively. Linear regression analysis data for the calibration plot showed that there was good linear relationship between response and concentration in the range of 10-60 μg/ml for both Amoxicillin trihydrate and Metronidazole, respectively. Percentage recoveries obtained for Amoxicillin trihydrate and Metronidazole were 99.79% and 100.33% respectively. The proposed method is precise, accurate, selective and rapid for the simultaneous determination of Amoxicillin trihydrate and Metronidazole in pharmaceutical dosage forms. Keywords: Simultaneous Estimation, Amoxicillin Trihydrate and Metronidazole