During the fourth period, subjects will receive once daily oral doses of 40 mg omeprazole for 6 days (Days 10 through 16). Subjects will fast on the evening of the fourth day for at least 10 hours prior to receiving the last treatment, which is a single dose of 160 mg GED 0301 together with one 40 mg oral dose of omeprazole (Day 15). On Day 16, subjects will take the last dose of omeprazole.