Simple spectrophotometric methods for the determination of metronidazole and spiramycin in tablets

Background: To develop and validate two simple and precise ultraviolet (UV)spectrophotometric methods for the simultaneous determination of metronidazole (MET) and spiramycin (SPI) in tablet formulations.Methods: Two methods, absorbance subtraction and absorbance correction, were employed.Absorbance measurements were taken at 232 nm, where both MET and SPI absorb, and at 311 nm, where only MET absorbs.The linear concentration ranges for MET and SPI were 6.25-31.25 and 7.95-39.75g/mL, respectively.Results: Both methods demonstrated good precision, with relative standard deviations (RSDs) below 2% for repeatability and intermediate precision.The accuracy of the methods was confirmed by the close agreement between the theoretical and actual concentrations of MET and SPI in nine synthetic mixtures, with RSDs remaining below 2%.Additionally, statistical comparison with a previously reported high-performance liquid chromatography method revealed no significant differences between the methods, as indicated by a P-value greater than the P-critical value (P > 0.05). Conclusion:The developed UV-spectrophotometric methods are accurate, precise, and suitable for the simultaneous determination of MET and SPI in tablet formulations.The methods provide a reliable alternative to more complex analytical techniques and can be applied for routine quality control purposes.