Ketamin (Calypsol)
Mechanism of action
Hypnotic and analgesic (phencyclidine derivative).
NMDA receptor antagonist causing dissociative anaesthesia.
Additionally has an effect on opioid mu, kappa and delta receptors and partial antagonist effect on muscarinic receptors (including bronchodilation). Also has mild local anaesthetic effects via sodium channel interaction.
Indications and dose
Useful in patients who are at risk of cardiovascular depression (hypotension).
Contraindications
Acute porphyrias
Head trauma
Raised intracranial pressure
Severe cardiac disease
Stroke
Eclampsia
Side-effects
Increased intracranial pressure
Increased salivation
Nausea and vomiting
Delirium and hallucinations
Pharmacokinetics
Onset of action: 30 seconds (IV); 6 minutes (IM)
Bioavailability: 20%
Distribution: 50% protein bound
Metabolism: mainly hepatic
Half-life of elimination:
Excretion: Urine
Directions for administration
Dilute in 5% glucose or 0.9% sodium chloride.
For continuous intravenous infusion use concentration of 1 mg/ml.
For intravenous injection dilute to less than 50 mg/ml strength.
Can be administered centrally or peripherally.
To decrease risk of respiratory depression, give intravenous boluses over 30-60 seconds.
Medicinal forms
Routes: intravenous, intramuscular, oral, extradural, intrathecal, nasal, intraosseous
Solution for injection - vials e.g. 10 ml = 500 miligrams (1 ml=50 mg)
References
