The goal of this study is to determine whether a single dose of AMX has an appreciable effect on upper gastrointestinal motility compared to placebo. In particular, induction of phase III of the interdigestive migrating motor complex (MMC) by AMX will be the primary outcome of the study. MMCs are periodic waves of electrical activity resulting in muscular contractions that pass through the walls of the stomach and intestinal tract during the fasting state. It is characterized by an initial period where there is a minimal electrical activity and muscular contraction (phase I), followed by a gradual increase in the frequency of contractions (phase III) that often leads to a characteristic cluster of contractions (phase III). This cycle occurs only in the fasting state in normal individuals and the frequency of phase III is quite varied, dependent on age and the presence of any underlying abnormalities in gastrointestinal motility. Secondary outcomes will include characteristics of the MMC, patient demographics in responders and non-responders, and the safety profile of AMX at the intervention dose.