Pharmacokinetics and bioequivalence of two methylprednisolone tablet formulations in healthy Chinese subjects under fasting and fed conditions.

Aims: The aims of this study were to evaluate and compare the pharmacokinetic profiles and bioequivalence of two tablet formulations of methylprednisolone (test formulation: Zhejiang Xianju Pharmaceutical Co., Ltd., China; reference formulation: Medrol, Pfizer Italia SRL) in healthy Chinese subjects under fasting and fed conditions.

Materials and methods: Subjects were randomly allocated to either the fasting group or the fed group and also to one of two sequences (test-reference or reference-test), according to which they received a single 16-mg dose of the test or reference methylprednisolone tablet in the study periods. Blood samples were collected pre dose and at intervals up to 16 hours after administration. Plasma methylprednisolone concentrations were determined using a validated liquid chromatography tandem mass spectrometry method. The safety of the medications was monitored throughout the study. The primary pharmacokinetic parameters measured were C_max, AUC_0-t, and AUC_0-∞.

Results: A total of 56 subjects were enrolled, and all completed the study. The 90% confidence intervals for C_max, AUC_0-t, and AUC_0-∞, measured under both fasting and fed conditions, fell within the acceptable range for bioequivalence of 80 - 125%. Analysis of variance showed that there were no significant differences in the primary pharmacokinetic parameters (C_max, AUC_0-t, and AUC_0-∞) between the test and reference formulation measured under both fasted and fed conditions. No serious or unexpected adverse drug reactions occurred during the study period.

Conclusion: The test methylprednisolone 16 mg tablet produced in China is bioequivalent to the reference formulation (Medrol) in healthy Chinese subjects measured under both fasting and fed conditions. Both formulations were well tolerated by all study participants.