Bioequivalence and Safety Assessment of Two Formulations of Metformin Hydrochloride Sustained-Release Tablets (Yuantang(®) SR and Glucophage(®) XR) Under Fed Conditions in Healthy Chinese Adult Subjects: An Open-Label, Two-Way Crossover, Sequence Randomized Phase I Clinical Trial

OBJECTIVE: The purpose of this single-center, randomized, open, two-period, two-sequence crossover, single-dose administration, bioequivalence research was to evaluate the bioequivalence and safety of the generic formulations of metformin hydrochloride sustained-release (MH-SR) 500 mg tablets (test preparation [T]: Yuantang(®) SR) and the original formulation (reference preparation [R]: Glucophage(®) XR) in 36 healthy Chinese volunteers under postprandial conditions. METHODS: Subjects received 500 mg T/R in each period, with a 7-day washout period. Venous blood samples of 4 mL each were collected from each subject 19 times spanning predose (0 h) to 36 h postdose. The metformin concentration in deproteinized plasma was determined by high-performance liquid chromatography–tandem mass spectrometry. Bioequivalence (80.00–125.00%) was assessed by adjusted geometric mean ratios (GMRs) and two-sided 90% confidence intervals (CIs) of the area under the curve (AUC) and maximum concentration (C(max)) for each component. SAS 9.4 software was used for statistical analysis and Phoenix WinNonlin software v7 was used to analyze the pharmacokinetic parameters. RESULTS: Thirty-four volunteers completed the clinical study. The 90% CIs (96.12–105.44% for AUC from time zero to the time of the last measurable concentration [AUC(t)], 96.22–105.54% for AUC extrapolated from time zero to infinity [AUC(∞)], and 98.42–105.00% for C(max)) of T/R adjusted GMRs were within the bioequivalence acceptance range of 80.00–125.00%, indicating that they are bioequivalent. No serious adverse events occurred in this study, indicating that the two formulations were effective and well tolerated. CONCLUSIONS: Yuantang(®) SR was confirmed to be a well tolerated and bioequivalent alternative to Glucophage(®) XR when taken under postprandial conditions in healthy Chinese volunteers. The Clinical Trials Registry Platform used for this study was http://www.chinadrugtrials.org.cn/clinicaltrials.searchlistdetail.dhtml. The trial registration numbers (TRNs) and dates of registrations were CTR20180476 (19 April 2018) for this clinical trial and CTR20171595 (11 January 2018) for the pilot trial.