Bioequivalence Study of Two Formulations of Mifepristone Tablets in Healthy Chinese Subjects Under Fasting Conditions

A single-dose, open-label, randomized, two-period crossover-design study was conducted to evaluate the bioequivalence of the reference and test formulations of mifepristone tablets. Each subject was randomized at the beginning to receive a 25-mg tablet of the test or the reference mifepristone under fasting conditions during the first period, then received the alternate formulation during the second period following a 2-week washout period. A validated high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was used to determine the plasma concentrations of mifepristone and its two metabolites (RU42633 and RU42698). Fifty-two healthy subjects were enrolled in this trial, 50 of whom completed the study. The 90% confidence intervals for the log-transformed Cmax , AUC0-t , and AUC0-∞ fell within the accepted 80%-125% range. Throughout the study period, a total of 58 treatment-emergent adverse events were reported. No serious adverse event was observed. In conclusion, the test and reference mifepristone were bioequivalent and well tolerated under fasting conditions.