Domperidone

Domperidone is a dopamine D₂-receptor antagonist used mainly to relieve nausea and vomiting and to promote movement through the stomach. It acts chiefly outside the brain because it crosses the blood–brain barrier poorly.

Dopamine receptor D₂: A G protein-coupled receptor that responds to dopamine and helps regulate movement, hormone release, and other functions. Domperidone blocks this receptor to increase gut motility and reduce nausea.
Nausea: The unpleasant sensation of impending vomiting, which may occur with or without actual emesis. Relieving nausea is one of domperidone’s main intended effects.
Metoclopramide: A dopamine D₂-receptor antagonist used for nausea and delayed gastric emptying that readily enters the brain. Unlike domperidone, it more often causes central neurological effects such as movement disorders.
Torsades de pointes: A potentially life-threatening polymorphic ventricular tachycardia associated with prolonged cardiac repolarization. It is a rare but serious arrhythmia associated with medicines that prolong the QT interval.
Chemoreceptor trigger zone: A brainstem region that detects blood-borne substances and can activate vomiting. Domperidone suppresses nausea partly by blocking dopamine signaling in this region.
Gastroparesis: Delayed stomach emptying without a mechanical blockage, often accompanied by nausea and fullness. Domperidone may be used to improve symptoms by promoting gastric emptying.
Ondansetron: A serotonin 5-HT₃-receptor antagonist used to prevent nausea and vomiting. It relieves nausea through serotonin blockade rather than domperidone’s dopamine antagonism.
Sudden cardiac death: An unexpected death caused by abrupt loss of effective heart function. Studies linking domperidone with ventricular arrhythmias have raised concern about this outcome.
Gastrointestinal motility: The muscular contractions that move food and contents through the digestive tract. Domperidone promotes stomach emptying by enhancing upper-gut motility.
Parkinson's disease: A progressive neurological disorder involving loss of dopamine-producing neurons and impaired movement. Domperidone may treat nausea caused by Parkinson’s medicines without readily entering the brain.

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ApomorphineRelated: It can reduce apomorphine-related nausea while generally avoiding blockade of its central motor effects.