Bioequivalence study of two formulations of memantine hydrochloride tablets in healthy male Chinese subjects under fasting and fed conditions

Purpose: Memantine is currently the only drug that acts on the glutamate energy system to treat Alzheimer's disease. A generic memantine tablet was developed to offer an alternative to the marketed tablet formulation. The purpose of this study was to assess the bioequivalence of two different memantine formulations among healthy male Chinese subjects under fasting and fed conditions. Materials and methods: We carried out single-center, randomized, single-dose, open-label, two-period, cross-over studies which including 20 healthy male Chinese subjects under fasting and fed conditions, respectively. Plasma samples were collected prior to and up to 240 hours after dosing. Key pharmacokinetic parameters including area under the plasma concentrationtime curve from time zero to the last measurable concentration (AUC(0-t)), area from time zero to infinite (AUC(0)(-infinity)), and C-max were used for biocquivalence assessment. Results: Under fasting condition, the 90% CIs of the geometric mean ratios of the test/reference drug for memantine were 106.5 - 114.0% for C-max, 99.4 - 107.9% for AUC(0-t), and 100.0 - 109.6% for AUC(0)(-infinity). Under fed condition. the 90% CIs of the geometric mean ratios of the test/reference drug for memantine were 94.8 - 104.3% for C-max, 98.2 - 110.5% for AUC(0)(-t), and 99.2 - 113.0% for AUC(0)(-infinity) Conclusion: The observed pharmacokinetic parameters of memantine of the test drug were similar to those of the reference formulation both in the fasting and fed state. That is to say, the test formulation of memantine 10-mg tablet is bioequivalent to the reference formulation (Ebixa 10-mg tablet).