Uncertainty in the Quantification of Metronidazole in Injectable Solution and its Application in the Assessment of Pharmaceutical Equivalence

Measurement uncertainty provides indication of the quality of the results and its usefulness for compliance or non-compliance decisions. On the other hand, pharmaceutical equivalence is an important step in confirmation of similarity and interchangeability of pharmaceutical products. The aim of this work was to establish a procedure to estimate the measurement uncertainty for metronidazole quantification by high performance liquid chromatography (HPLC) and apply this uncertainty in the assessment of pharmaceutical equivalence. According to our results, the expanded uncertainty of metronidazole quantification by HPLC was about 3.5%, considering a coverage factor of 2.00 and a 95% confidence level. Uncertainties associated to the accuracy, precision and area of the peaks are the most significant. The measurement uncertainty approach was compared to the two one-sided tests (TOST) for equivalence. Both tests allow us to confirm pharmaceutical equivalence among generic and reference products and similar and reference products of metronidazole injection.