Phase III, Long-term, Open-label Safety Study of Z-338

Inclusion Criteria: * Subjects to provide written informed consent prior to any study procedures being performed * Subjects with a diagnosis of FD (postprandial distress syndrome) as defined by the Rome III Criteria * Subjects must present Postprandial Fullness or Early Satiation as the most bothersome symptom during the 6 months prior to informed consent. * Subjects must have a normal endoscopy result within the 6 months (3 months in case of subjects who are Helicobacter pylori positive) prior to informed consent or during the screening period. Exclusion Criteria: * Subjects on PPI(s) who are unable to discontinue PPI medication by the end of the screening period * Subjects taking drugs that affect gut motility, gut sensitivity and/or acid secretion who are unable to discontinue these drugs by the end of the screening period * Subjects who have received H. pylori eradication therapy during the 3 months prior to informed consent * Subjects with confirmed organic gastrointestinal disease * Subjects presenting with predominant complaints relieved by stool movements (irritable bowel syndrome) * Subjects presenting with predominant GORD symptoms * Subjects presenting with predominant complaints of chronic idiopathic nausea * Subjects with Type I or Type II diabetes * Subjects with body mass index (BMI) over 30 kg/m2 * Subjects with any condition which, in the opinion of the Investigator, makes the subject unsuitable for entry into the study