Study population
Subjects were Japanese males aged between 20 and 46 years, with a body mass index between ≥ 18.5 and < 25.0 kg m-2 -1. Eligible subjects had no clinically problematic abnormalities regarding their medical findings, vital signs, electrocardiogram, and laboratory tests, and the investigator determined that there were no problems that would have prevented participation in this study. The following subjects were excluded: those who had a previous or current history of functional disorders related to the liver, heart, kidney, lungs, blood, gastrointestinal tract, or any other disorders that would preclude their participation; a previous or current history of upper gastrointestinal disorders; a history of drug allergy; white blood cell count ≤ 4000 µL-1; neurological symptoms; a previous or current history of serious infectious diseases, including opportunistic infections within 1 year prior to administration of the study drug; ingestion of grapefruit, grapefruit juice or foods containing these ingredients within 8 days prior to the start of administration of the study drug; or ingestion of St. John’s Wort or foods containing these ingredients within 15 days prior to the start of administration of the study drug.