Ketamine

CLASS

  • phencyclidine derivative hypnotic and analgesic

MECHANISM OF ACTION

  • NMDA receptor antagonist resulting in dissociative anaesthesia (profound analgesia with superficial sleep)
  • interacts with opioid receptors – mu, delta and kappa
  • muscarinic receptors – partial antagonist effect (bronchodilation, sympathomimetic, delirium)
  • Na+ channel – mild LA like properties

PHARMACEUTICS

  • colourless solution, 10/50/100mg/mL, racemic, benzethonium chloride (preservative)

DOSE

  • IV, IM or PO, extradural, intrethcal, rectal or nasal
  • IM – 10mg/kg (6min onset)
  • IV – 2mg/kg (30 sec onset) or rate of 50mcg/kg/min
  • analgesic dose: 0.1-0.3mg/kg -> 0.1mg/kg/hr

INDICATIONS

  • induction of anaesthesia and emergency intubation
    • asthma
    • hypotension/ haemodynamic instability (e.g. trauma, sepsis)
    • severe metabolic acidosis (allowing spontaneous ventilation)
    • delayed sequence intubation to allow preoxygenation with spontaneous ventilation
  • procedural sedation (especially for children, prehospital, and in mass casualties)
  • analgesia – perioperative and chronic pain
  • severe unresponsive asthma (bronchodilator)
  • refractory status epilepticus
  • controversial role in the treatment of depression

ADVERSE EFFECTS

  • salivation
  • increased ICP (although newer data questions this)
  • PONV
  • emergence delirium -> hallucinations

PHARMACOKINETICS

  • Absorption – bioavailability = 20%
  • Distribution – t1/2 alpha = 10 min, 50% protein bound, Vd 1.8L/kg
  • Metabolism – hepatic, some active metabolites
  • Elimination – t1/2 beta = 2.5 hrs, urinary

OTHER INFORMATION

  • Ketamine can be used for refractory status epilepticus (observational studies suggest ketamine is an effective option for refractory status epilepticus due to antagonism of excitotoxic NMDA receptors) (Hofler and Trinka, 2018)

References and links

  • Höfler J, Trinka E. Intravenous ketamine in status epilepticus. Epilepsia. 2018;59 Suppl 2:198-206. [pubmed]

CCC 700 6

Critical Care

Compendium

One comment

  1. Hi!

    Thank you for this great summary regarding Ketamine!
    I’m trying to find out through which mechanism Ketamine causes hypersalivation. Would you mind helping me please?
    Thank you!
    Betul Korkmaz

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