Domperidone is a selective peripheral dopamine receptor (D2) antagonist used to optimize upper gastrointestinal motility. It functions primarily by blocking D2 receptors in both the chemoreceptor trigger zone (CTZ) and the muscular walls of the upper gut. Because it poorly crosses the blood-brain barrier, its actions are tightly focused on peripheral pathways: it enhances antral and duodenal contractions, relaxes the pyloric sphincter, and increases lower esophageal sphincter tone to accelerate gastric emptying while systematically preventing nausea and vomiting signals.