Metoclopramide in Anaesthesia

Actions

• Increases lower oesophageal sphincter tone.
• Increases gastric antral contractions and promotes gastric emptying.
• Reduces gastric fluid volume but does not reduce gastric acidity.
• Antiemetic action is through dopamine blockade in the chemoreceptor trigger zone.

Anaesthetic uses

1. Aspiration prophylaxis: Used in patients at increased risk of regurgitation and aspiration, such as emergency surgery, inadequate fasting, diabetes with gastroparesis, obesity, and obstetric patients when clinically indicated.
2. Treatment/prevention of nausea and vomiting: May be used perioperatively, though other antiemetics are often preferred for routine PONV prophylaxis.
3. Facilitates gastric emptying and passage of nasogastric/intestinal tubes in selected patients.

Dose

• 10 mg IV, usually administered slowly about 30 minutes before induction.
• Oral dose: 10-15 mg, with variable onset.
• IV onset is about 1-3 minutes; duration about 1-2 hours.
  Morgan and Mikhail’s Clinical Anesthesiology, 7e, p. 509.

Adverse effects

• Drowsiness, restlessness, agitation.
• Abdominal cramps and diarrhoea, especially after rapid IV injection.
• Extrapyramidal effects: acute dystonia, akathisia, parkinsonism.
• Tardive dyskinesia with repeated or prolonged exposure.
• Rarely: neuroleptic malignant syndrome and hyperprolactinaemia.

Contraindications / precautions

• Gastrointestinal haemorrhage, mechanical obstruction, or perforation.
• Phaeochromocytoma: may provoke hypertensive crisis.
• History of tardive dyskinesia or dystonic reaction.
• Caution with Parkinson disease and concurrent antipsychotic drugs because extrapyramidal toxicity is increased.
• Antimuscarinics such as atropine and glycopyrrolate antagonise its gastrointestinal prokinetic effect.