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metoclopramide

metoclopramide (Maxolon)

introduction

  • a commonly used anti-emetic agent
  • actions include:
    • 5-HT3 antagonist
      • ⇒ actions on GIT myenteric plexus:
        • ⇒ decreased bowel hypermotility & increased gastric emptying
      • ⇒ actions on CNS:
        • ⇒ anxiolytic, neuroleptic, & blocks CTZ/vomiting centre
    • 5-HT4 agonist
      • GIT neuroexcitatory ⇒ diarrhoea
      • CNS effects
      • cardiac muscle stimulation
    • CNS dopamine D2 antagonist
    • peripheral dopamine D2 antagonist (thus reduced inhibition of cholinergic smooth muscle stimulation in GIT)
      • ⇒prokinetic actions in GIT

adverse effects

  • main adverse effects are extrapyramidal effects including:
    • dystonic reactions and oculogyric crises
      • these are usually self-limiting and rarely cause permanent damage, but they are alarming to the patient
      • generally occur within 72 hours of exposure to metoclopramide
      • highest risk tend to be younger patients with only 10% of cases occurring in those > 40yrs age
      • the higher risk in children means that it should be avoided in childhood
    • akathisia
      • defined as a movement disorder characterised by a feeling of inner restlessness and anxiety
      • symptoms ranging from mild restlessness to high levels of anxiety.
      • occurs in ~10-15% of patients receiving iv doses or infusions of 10-20mg in ED
    • exacerbation of restless legs syndrome
    • permanent, rarely reversible, tardive dyskinesia
      • this is an extremely troubling adverse effect and risk is related to:
        • older age
        • female gender
        • duration of treatment / number of doses
      • does not reverse even on withdrawal of metoclopramide
      • thus avoid long term dosing

contraindications

  • children - as high incidence of adverse reactions
  • PH hypersensitivity or significant adverse reactions

clinical usage

  • commonly used as a first line anti-emetic in the ED
  • although often given prophylactically to combat the emetic effects of parenteral doses of opiates and opioids, there is little evidence to support this usage and exposes the patient to a significant risk of troubling akathisia unnecessarily.
  • if vomiting persists and an alternative anti-emetic is indicated, then second line is usually the more expensive ondansetron

dosage

  • 10mg iv, im or orally 6-8hrly prn in adults
metoclopramide.txt · Last modified: 2014/05/05 16:44 (external edit)