A Bioequivalence Study of Two Formulations of Enzalutamide Soft Capsules in Healthy Chinese Male Subjects

Abstract

Enzalutamide is an oral second‐generation androgen receptor inhibitor used for advanced prostate cancer. This study evaluated the pharmacokinetics (PK), bioequivalence (BE), and safety of a newly developed generic enzalutamide soft capsule (test) compared with the reference product (XTANDI) in healthy Chinese adults under fasting and fed conditions. A single‐center, randomized, open‐label, two‐period, two‐sequence, crossover study was conducted in 72 male participants (36 fasting and 36 fed). Each participant received a single 40‐mg dose of test or reference formulation, separated by a 34‐day washout. Blood samples were collected up to 72 h post‐dose. PK parameters (C _max and AUC _0‐72 h ) were calculated using non‐compartmental analysis. BE was assessed by 90% confidence intervals (CIs) of geometric mean ratios (GMRs). Safety was monitored throughout the study. In both fasting and fed conditions, the 90% CIs of GMRs for C _max and AUC _0‐72 h were within the predefined 80%–125% BE range. Both formulations exhibited a favorable single‐dose safety profile, with no serious adverse events reported. The test enzalutamide soft capsule is bioequivalent to the reference product in healthy Chinese volunteers, demonstrating similar PK profiles and safety. This study provides population‐specific PK evidence supporting the clinical use of the generic formulation in China.