The study population consisted of 4 Cohorts with 12 participants in each Cohort; with 9 participants randomized to receive a single dose of TAK-438, and 3 participants to receive placebo. Participants in each Cohort received a single dose of study drug once daily after a 10-hour fast. The starting dose was 10 mg followed by administrations of 20, 40, and 30 mg.