COMPARATIVE IN-VITRO BIOEQUIVALENCE STUDIES OF SOME BRANDS OF METRONIDAZOLE TABLET MARKETED IN ZARIA, KADUNA STATE

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Department of Pharmaceutical Sciences

ABSTRACT
Metronidazole is an antibacterial and antiprotozoal drug used in the treatment of amebiasis, giardiasis, trichomoniasis and other microbial diseases. It is an essential drug commonly found in Nigerian market and has so many generics and dosage forms under various trade names by different manufacturers. The purpose of the study was to evaluate and compare the in-vitro bioequivalence of branded and generic metronidazole tablet in three different physiological media (pH 1.2, 4.5 and 6.8). Six brands of metronidazole tablet were randomly selected from different areas of Zaria town and evaluated for quality via identification test, assay, weight variation test, disintegration time test, friability, crushing strength and dissolution. Three UV spectrophotometric methods were developed, validated and used for determining the amount of metronidazole release during the in-vitro dissolution studies. The percentage of metronidazole released was then subjected to in-vitro bioequivalence comparison using the model independent method of comparism. The results showed that all brands passed identification an assay test except brand MD and ME that failed the assay test. The tested brands passed weight variation test, disintegration time test, friability and hardness except brand ME which failed the hardness test. Wavelength of maximum absorbance (?max) of 295nm, 345nm and 350nm were recorded for metronidazole in pH media 1.2, 4.5 and 6.8 respectively, with a linear relation at concentration range of 2-64?g/mL. The correlation coefficients were close to unity with percentage recoveries ranging from 98-102% and precision (% CV) <15%. The in-vitro dissolution profile studies showed that brand MB and MC are similar with brand MA at difference factor (f1) ≤15 and similarity factor (f2) >50; therefore, can be used interchangeable with brand MA in all the three simulated physiological media. Also, brand MF had similar dissolution profile with MA in two physiological media (pH 1.2 and 4.5) but not in pH 6.8. However, the dissolution profile of brand MD and brand ME were not similar with brand MA in all the three media. The percentage dissolution efficiency (DE) of all the brands in all the three media were within the acceptable limit of ±10%. It was concluded that the branded MA could be interchanged with brand MB and brand MC in all the three media and with brand MF in pH 1.2 and pH 4.5 but not in pH 6.8 and also not with brand MD and brand ME in all the three media.