Evaluation of reference-scaled average bioequivalence of two oral formulations of abiraterone acetate in healthy Chinese subjects

Objective: This study was designed to evaluate the pharmacokinetic (PK) properties and bioequivalence (BE) of two 250-mg tablet formulations of abiraterone acetate: a newly developed generic formulation (test) and a branded formulation (reference) in healthy adult Chinese subjects under fasted (n = 40) and fed (n = 40) conditions. Materials and methods: The comparison was performed using a single-dose, open, randomized, and four-way replicate study. The concentration of abiraterone in blood samples taken over 48 hours was determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). To assess the BE of the test and reference formulations, confidence intervals (CI, 90%) for the peak plasma concentration (C-max) and area under the concentration-time curves (AUC(0-t) and AUC(0-infinity)) were calculated using the reference-scaled average bioequivalence (RSABE) method. Results: The results showed that the 90% CIs for the ratios of C-max, AUC(0-t), and AUC(0-infinity), in the fasted study were 90.14 - 114.11, 93.96 - 115.07, and 93.72 - 113.331, respectively. For the fed study, the 90% CIs were 81.83 - 102.51, 91.51 - 104.89, and 91.46 - 104.58, respectively. Conclusion: In conclusion, the tested 250-mg abiraterone tablets were bioequivalent to 250-mg Zytiga tablets (reference) under both fasted and fed conditions. In addition, food intake increased the systemic exposure and C-max of abiraterone by 3-fold and 7-fold, respectively.