Dopamine antagonist antiemetics

These drugs block dopamine D2 receptors in the gut wall and in the chemoreceptor trigger zone, a brainstem site the blood-brain barrier does not shield. The gut effect raises lower esophageal sphincter tone and speeds gastric emptying, so they are prokinetic as well as antiemetic, and both raise prolactin. Metoclopramide also acts in the brain and can cause movement disorders; domperidone barely gets in.

• MetoclopramideA dopamine D2 antagonist and prokinetic for nausea and vomiting, diabetic gastroparesis and reflux; it can cause movement disorders.
• DomperidoneNot approved in the US. After a 2014 review of its heart risks, the EU kept it only for nausea and vomiting, at lower doses and for about a week.

• Nausea and vomiting
• Nausea and vomiting from chemotherapy or radiotherapy
• Nausea and vomiting after surgery
• Slow stomach emptying in diabetes (gastroparesis)

• Acute dystonia and drug-induced parkinsonismKnown forSerious
• Tardive dyskinesiaKnown forSerious
• Raised prolactin: breast milk leakage, missed periodsKnown for
• Drowsiness and tiredness
• Restlessness (akathisia)
• Breast enlargement in men (gynecomastia)
• QT prolongation and ventricular arrhythmiasSerious
• Neuroleptic malignant syndromeSerious
• Dry mouth
• SeizuresSerious

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• Contraindicated with gut bleeding, obstruction or perforation, where faster gut movement could do harm.
• Contraindicated in pheochromocytoma, where they can set off a hypertensive crisis.
• Short courses only: the EU limits metoclopramide to 5 days and domperidone usually to a week.
• Risks rise with age: tardive dyskinesia with metoclopramide, and sudden cardiac death with domperidone over 60.

Written for biofideX in plain words, after checking these references:

• Metoclopramide tablets: label (DailyMed)
• Domperidone 1mg/ml oral suspension: SmPC (eMC)
• Domperidone-containing medicines: referral (EMA)
• Metoclopramide-containing medicines: referral (EMA)
• Metoclopramide (NHS)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.