Development and validation of a simple HPLC method for simultaneous in vitro determination of amoxicillin and metronidazole at single wavelength

A simple, rapid, sensitive and robust reversed phase-HPLC method was developed and validated to measure simultaneously the amount of amoxicillin and metronidazole at single wavelength (254 nm) in order to assess drug release profiles and drug-excipients compatibility studies for a new floating-sustained release tablet formulation and its subsequent stability studies. An isocratic elution of filtered sample was performed on C18 column with buffered mobile phase (pH 4.0) and UV detection at 254 nm. Quantification was achieved with reference to the external standards. The linearity for concentrations between 0.15 and 600 microg/ml for amoxicillin and 0.13 and 300 microg/ml for metronidazole were established. Intra and inter-day precision were less than 2.5%. The limits of detection (LOD) and quantification were 0.05 and 0.15 microg/ml for amoxicillin and 0.10 and 0.13 microg/ml for metronidazole. The determination of the two active ingredients was not interfered by the excipients of the products. Samples were stable in the release media (37 degrees C) and the HPLC injector at least for 12 h.