Metocopramide

Question 1

What is the generic name of Metoclopramide?

Answer 1

Metoclopramide hydrochloride monohydrate

Question 2

What type of medication is metoclopramide?

Answer 2

Anti-nauseant and anti-emetic.

Question 3

What is the route, onset, peak and duration for metoclopramide?

Answer 3

• Route: IM
  
  • Onset: 10-15min
  • Peak: N/A
  • Duration: 1-2hrs
• Route: IV
  
  • Onset: 3-5min
  • Peak: N/A
  • Duration: 1-2hrs

Question 4

What are the NSW Ambulance uses for Metoclopramide?

Answer 4

• Nausea & vomiting: Patients 16yo or more with severe nausea and/or active vomiting where ondansetron is contraindicated/ineffective after 10 min.
• Eye injuries: Patients 16yo or more with suspected penetrating eye injuries where ondansetron is contraindicated or ineffective after 10 min. (this is to prevent expulsion of ocular contents due to raised intraocular pressure from vomiting).

Question 5

What are the adverse effects of metoclopramide?

Answer 5

• restlessness/drowsiness and fatigue
• extrapyramidal/acute distonic reactions including spasms of the face, trismus, rhythmic protrusions of the tongue, abnormal speech, spasm of the extra occular muscles and unatural positioning.

Question 6

What are the contraindications of metoclopramide?

Answer 6

• Patients < 16 yrs of age
• Previous history of extrapyramidal/dystonic reaction
• Patients with Parkinson’s Disease
• Allergy or hypersensitivity to metoclopramide
• Suspected bowel obstruction
• Suspected or known haematemesis or melaena

Question 7

What is the preparation of Metoclopramide? Are repeat doses allowed?

Answer 7

One 10mg (2ml) ampoule, delivered IV/IM.

Nil repeates, max dose 10mg.

Question 8

What is the mechanism of action of Metoclopramide?

Answer 8

Metoclopramide antagonises central and peripheral dopamine D2 receptors (These are normally stimulated by levodopa or apomorphine(1) ) and Seratonin 5-HT3 receptors in the medullary chemoreceptor trigger zone.

The antagonism is achieved by decreasing the sensitivity of visceral afferent nerves(2) that transmit from the GI system to the vomiting center(3). It also blocks the antiperistaltic effects of apomorphine(4) , accelerating gastric emptying by increasing peristalsis.

It is also a 5-HT4 receptor agonist. This increases the release of acetylcholine, causing increased lower esophageal sphincter (LES) and gastric tone, accelerating peristalsis and gastric emptying.

(1) Apomorphine is a type of D1/D2 dopamine receptor agonist, a morphine derivative (it contains no morphine and doesn’t bind to opioid receptors). It is a powerful emetic, acting on the dopamine receptors in the vomiting center of the brain.
(2) Nerves that transmit sensory signals such as pain from the internal organs, glands and blood vessels to the brain.
(3) This is located in the area postrema in the chemoreceptor trigger zone.
(4) Dopamine exerts relaxant effects on the GI tract through binding to muscular D2 receptors. Apomorphine antagonises these receptors.