In Vitro Equivalence Studies And Comparative Assessment Of Generic Metronidazole Tablets Commercially Available Under Biowaiver Conditions In Nigeria.

ABSTRACT

The aim of the present study was to investigate the physicochemical equivalence and compare

the dissolution rate of thirteen brands of metronidazole tablets collected from retail

pharmacies in Nigerian markets.

This study sought to apply the BCS biowaiver requirements to assess the equivalence of

commonly interchanged generic Metronidazole tablets with their innovator product in

Nigeria.

Solubility of active pharmaceutical ingredients (API) has always been a concern for

formulators, since poor aqueous solubility may hamper development of drugs and limit

bioavailability of oral products. 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 quality and physicochemical equivalence of thirteen different brands of metronidazole

tablets were assessed. The assessment included the evaluation of uniformity of weight,

friability, breaking force /hardness test, disintegration and dissolution tests as well as chemical

assay of the tablets.

All the thirteen brands of the tablets passed the British Pharmacopoeia (BP) standards for

uniformity of weight, two brands, MZ-3 and MZ-13 giving 29.6 minutes and 18mins

respectively failed the disintegration and friability test. Six of them failed the breaking

force/hardness test. There were insignificant differences in the dissolution profiles of nine (9)

brands. All the brands except MZ3, MZ4, MZ10 and MZ13 released >85% of Metronidazole

within 30 min showing 50.89%, 16.89%, 13.14% and 59.44% respectively in pH 1.2 and

64.80%, 20.89%, 15.80% and 48.77% in pH 6.8 respectively as such these brands should not

be used interchangeably with the innovator’s brand. Only nine of the brands complied with

the standard assay of active ingredients content for Metronidazole.

The brands of metronidazole tablets that did not pass all the BP or USP quality specifications

are regarded as not physically and chemically equivalent.

This study highlights the need for constant market monitoring of new products to ascertain

their equivalency to the innovator product.