Metoclopramide
A dopamine D2 antagonist and prokinetic for nausea and vomiting, diabetic gastroparesis and reflux; it can cause movement disorders.
Drug card
- How it works
- Blocking dopamine D2 receptors in the trigger zone and the gut
- Used for
- Nausea and vomiting, including with migraine
- Nausea and vomiting from chemotherapy or radiotherapy
- Nausea and vomiting after surgery
- Diabetic gastroparesis
- Known for
- Tardive dyskinesia, often irreversible
- Acute dystonia and drug-induced parkinsonism
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does metoclopramide work?
Blocks D2 receptors in the chemoreceptor trigger zone and in the gut, where it also seems to sensitize smooth muscle to acetylcholine. It strengthens antral contractions, relaxes the pylorus and raises lower esophageal sphincter tone, so the stomach empties faster, with little effect on the colon. Its central dopamine block causes its extrapyramidal effects.
Like other 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.
Uses
What is metoclopramide used for?
- Nausea and vomiting, including with migraine
- Nausea and vomiting from chemotherapy or radiotherapy
- Nausea and vomiting after surgery
- Diabetic gastroparesis
- Reflux disease that fails other treatment
Side effects
Side effects of metoclopramide
- Tardive dyskinesia, often irreversibleKnown forSerious
- Acute dystonia and drug-induced parkinsonismKnown forSerious
- Restlessness (akathisia)
- Drowsiness and tiredness
- Neuroleptic malignant syndromeSerious
- Depression and suicidal thoughtsSerious
- Raised prolactin: galactorrhea, gynecomastia, amenorrhea
- Fluid retention
- Raised blood pressureSerious
- SeizuresSerious
- Diarrhea
- Slow heart rateSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Tardive dyskinesia risk grows with time and total dose: the US limits use to 12 weeks, the EU to 5 days.
- Contraindicated in epilepsy, pheochromocytoma and gut bleeding, obstruction or perforation.
- Avoid in Parkinson's disease and with antipsychotics, which add to its dopamine block.
- Acute dystonia is likelier in children and young adults; it should not be used under 1 year of age.
Remember it
A way to remember it
Domperidone stays outside the brain; metoclopramide moves in.
Both block D2 receptors in the trigger zone, which sits outside the blood-brain barrier. Domperidone hardly crosses the barrier, so movement disorders are very rare with it, while metoclopramide does cross and can cause dystonia and tardive dyskinesia.
Written for biofideX
Its class
Dopamine antagonist antiemetics
Other dopamine antagonist antiemetics with a card:
Easily mixed up with 5-HT3 antagonists and first-generation antipsychotics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Metoclopramide tablets: label (DailyMed)
- Metoclopramide (NCI Thesaurus)
- Metoclopramide (NHS)
- Metoclopramide-containing medicines: referral (EMA)
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.
Stomach and gut
Metoclopramide is one of 15 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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