In vitro comparative quality evaluation of different brands of metformin hydrochloride tablets available in Mekelle City, Tigray Regional State, Ethiopia

Administration of poor-quality medications can result in various effects that jeopardize the drugs’ safety and effectiveness. Due to a lack of adequate post-market surveillance studies, making decisions regarding the quality of medicines, including metformin hydrochloride tablets, available in Mekelle City is challenging. Thus, the aim of the study was to evaluate the quality of different brands of metformin hydrochloride tablets sold in Mekelle City, Tigray Regional State, Ethiopia. A total of eight brands of 500 mg metformin hydrochloride tablets were collected from drug retail outlets in Mekelle City. In vitro quality control tests were conducted based on the WHO visual inspection tool and United States Pharmacopeia (USP) specifications. These included visual inspection, weight variation, thickness, hardness, friability, disintegration time, dissolution, and an assay of active ingredient. One-way ANOVA was used to compare all parameters of quality control. A difference was deemed statistically significant when P < 0.05. One-way ANOVA, model-independent approaches, and model-dependent approaches were used to compare the dissolution profiles and to determine the nature of active pharmaceutical ingredient release. This study showed that all metformin hydrochloride brands marketed in Mekelle City complied with the WHO visual inspection and USP specifications for visual inspection, weight variation, friability, disintegration time, and assay of the active ingredient. Of the samples tested, brand E and brand F exhibited the highest and lowest hardness values, respectively, at 313.88 N and 10.06 N. Moreover, all eight brands evaluated released more than 80% of their drug contents within 30 min as outlined in the USP. However, the difference factor (f1) and similarity factor (f2) have indicated that only brands A, E, and H were similar (can be used interchangeably) with the comparator product. Weibull release model suits the drug release data, which had the highest correlation coefficient. All brands met pharmacopoeial specifications, but significant variations in hardness and dissolution profiles were observed, with only three brands showing profile similarity to the comparator. Hence, the finding serves as an alert to examine the dossier evaluations and legal approval processes of the Ethiopian Food and Drug Authority.