A Study to Evaluate How a Drug That Alters Liver Enzymes (Rifampin) Affects the Metabolism of Enzalutamide in Men

The study consists of 2 randomized treatment arms. In both arms the subjects receive a single oral dose of enzalutamide. In Arm 1 the subjects are admitted to the clinic on Day -1 where they remain until Day 3. Each subject receives a single oral dose of enzalutamide, administered under fasted conditions on Day 1. Ambulant visits take place from Day 4 to Day 50. Full PK profiles are obtained for enzalutamide, Major Inactive Carboxylic Acid Metabolite (M1) and Active Metabolite N-desmethyl Enzalutamide (M2) from Day 1 up to Day 50 after intake of enzalutamide. In Arm 2 each subject receives a once-daily dose of rifampin on Days 1 to 21. On Day 8, a single oral dose of enzalutamide is administered under fasted conditions concomitantly with rifampin. Full PK profiles are obtained for enzalutamide, M1 and M2 from Day 8 up to Day 57 after intake of enzalutamide. An End of Study Visit (ESV) takes place between 7 and 10 days after the last PK sample or early withdrawal. Safety assessments are performed throughout the study.