Bioavailability of Different formulations of metformin hydrochloride in healthy volunteers : a comparative study

Abstract

Objective: To assess the bioavailability of a formulation of metformin hydrochloride 850 mg coated tablets as test, compared to a reference product with the same dosage form, in healthy volunteers of both genders. Method: This clinical trial was designed as randomised, comparative, single-dose, open-label, two-period, two-sequence, crossover study under fasting conditions. 28 healthy volunteers (fourteen men and fourteen women) took part in the study. The 850 mg coated tablets formulations were administered in a single dose orally. Blood samples were obtained prior to dosing and at 30 min, 1, 1:20; 1:40, 2, 2:20, 2:40; 3, 3:20, 3:40 4, 4:30, 5, 6, 8, 12, 16, 24 and 36 hours after drug administration with an one week washout period. Plasmatic concentrations of metformin were measured by specific and validated analytical methods based on high-performance liquid chromatography coupled to mass spectrometry (HPLC/MS). The pharmacokinetics parameter AUC0-36h, AUC0-∞ and Cmax were tested for bioequivalence after log transformation of data and ratios of Tmax were evaluated non parametrically. Findings: Data from this study showed that the test and the reference formulation presented similar results, within the acceptance range (80-125%) for AUC0-∞ (area under curve) and Cmax (maximum serum concentration of the drug) parameters, satisfying the bioequivalence criteria of the Brazilian Health Surveillance Agency and FDA. Conclusion: These results indicate that the two formulations of metformin hydrochloride 850 mg coated tablets are bioequivalent, thus, it will be possible to ensure interchangeability between them, which can generate market competition and better access to this treatment.