• Respiratory depression and apnoea common
  • Reduced response to hypercapnia
  • Suppression of laryngeal and pharyngeal reflexes:
    • Ideal drug to assist with placement of supraglottic airway devices
  • Reduced systemic vascular resistance, cardiac output and blood pressure:
    • Causes the most marked fall in BP of all induction agents
    • Hypotension is dose dependent
    • Vasodilatation possible mediated by nitric oxide release
  • Can cause reflex tachycardia but more usually bradycardia
  • Sedation and anaesthesia:
    • Dose dependent cortical depression
    • Best endpoint is loss of verbal contact with the patient
  • Excitatory movements:
    • Seen in up to 10% of patients at induction
    • Dystonic with choreiform elements
    • Not epileptiform in nature
  • Anti-epileptic:
    • Has been used to terminate status epilepticus
    • Reduced intracranial pressure, cerebral perfusion pressure and cerebral metabolic rate
  • Antiemetic effects (possibly D2-antagonist mediated)