<p>Metoclopramide blocks dopamine receptors and in higher doses, it also blocks serotonin receptors in chemoreceptor trigger zone of the CNS. It enhances the response to acetylcholine of tissue in upper GI tract causing enhanced motility and accelerated gastric emptying w/o stimulating gastric, biliary, or pancreatic secretions. It also increases lower esophageal sphincter tone.</p>