This is a randomized, double blind, placebo controlled, multicenter study designed to assess the safety and efficacy of DDP225 in patients with chronic functional vomiting. Male or female patients from 18 to 65 years of age with a functional vomiting history for at least 12 weeks in the preceding 12 months or cyclic vomiting history with at least 3 episodes in the previous 12 months are eligible. A total of 30 eligible patients with chronic functional vomiting will be enrolled.