In vitro Equivalence Studies/Comparative Assessment of Generic Metronidazole Tablets Commercially Available in Lagos, Nigeria

Purpose: For drug products to be interchangeably used by healthcare providers, formulation characteristics, which reflect variation within brands, batches and lots examined via dissolution profile analysis, must not show high statistical discrepancies. The objective of this study is to investigate the physicochemical and in vitro equivalence of thirteen brands of metronidazole tablets obtained from pharmacy retail outlets in Lagos, Nigeria.
Methods: Physicochemical characteristics comprising hardness, friability, drug content were evaluated in comparison with the innovator brand MZ-1. Dissolution data was analyzed using model dependent approach of dissolution efficiency and model independent approaches.
Results: The twelve generics brands were within compendial specified limits for hardness, friability, drug content and disintegration. Four of the brands MZ-3, 4, 10 and 13 were not pharmaceutically equivalent to the innovator brand MZ-1, Based on the results obtained from model-dependent method via dissolution efficiency where the release profile as a function of time was compared, the f1 and f2 deciding the difference or similarity between dissolution profiles were used adequately utilized to decide pharmaceutical equivalence.
Conclusion: The extent to which these differences affected the amount of active constituent released over time in comparison with the innovator product was evident as only 8 of the brands MZ-2, 5, 6, 7, 8, 9, 11, 12 could be considered to be bioequivalent and thus interchangeably used with the innovator product.