Receptors

Vestibular nuclei and labyrinth
  • Muscarinic ACh (M3)
  • H1
CTZ (chemoreceptor trigger zone)
  • D2
  • 5HT3
VC (vomiting centre)
  • M3
  • Some H1
Visceral afferents
  • M3 (vagus – gut, heart)
  • 5HT3 (gut)
Sensory
  • M3
Drugs

Antimuscarinics
  • Cyclizine
  • Hyoscine
  • Atropine
Antihistamines
  • Cyclizine
  • Promethazine
5HT3 antagonists
  • Ondansetron, granesetron
Dopamine antagonists
  • Prochlorperazine
  • Haloperidol
  • Metoclopramide
  • Domperidone
Others
  • Steroids (dexamethasone) – unclear mechanism
  • Cannabinoids - CTZ
  • Propofol - CTZ

SEs

Antimuscarinics
  • Dry mouth, dilated pupils, tachycardia, urinary retention, sedation (hyoscine), confusion (atropine)
Antidopaminergic
  • Extra-pyramidal and dystonic effects – unopposed ACh effects
Antiserotoninergic
  • Few SEs, headache
Steroids
  • Steroid psychosis, hyperglycaemia, fluid retention
Cannabinoids
  • Sedation, munchies