NALOXONE

  • Need to understand PK and PD well.
Structure/Class
  1. Pure competitive antagonist at the opioid receptor.
Pharmacodynamics
  1. High affinity for the µ receptor. Limited affinity for κ and δ receptors.
  2. When given alone (i.e. no agonist present) the drug is inert.
  3. When given with an agonist, it reverses the opioid effect completely in 1-3 minutes.
    • Respirations, level of consciousness, pupil size and awareness of pain are normalized.
  4. No tolerance nor withdrawal will develop.
Absorption/administration
  1. IV. IM may be used to prolonged duration of action.
Distribution
  1. Localised in highly perfused tissues.
  2. Short T ½ – 60 to 90 minutes.
Metabolism
  1. Hepatic
Excretion
  1. Renal
Indications
  1. Reverses opioid toxicity
  2. Diagnostic tool
Contraindications  
Special precautions
  1. Short T ½ – therefore, patient requires close monitoring and may need repeated doses.
  2. Can precipitate withdrawal symptoms.
  3. May precipitate APO due to sympathetic surge.
Interactions  
Adverse events  
Dosing/administration
  1. 0.1 to 0.4 mg, repeat as necessary. Also may be given IM.
Toxicology  
Withdrawal syndrome  
Special notes