Opioid antagonists

OPIOID ANTAGONISTS

Naloxone

  • No analgesic activity at all
  • Competitive antagonist at mu, kappa, and sigma receptor
  • Displaces morphine and other OPIOID from receptor site
  • Reverses all actions of the OPIOID and does it rather quickly 
  • Precipitate withdrawal person on heroin
  • Naloxone effects are seen in the first five minutes and it only lasts for 30 minutes:
  • Increase blood pressure
  • Metabolized same as morphine through glucuronic acid and excreted through kidney

Naltrexone

  • Almost similar to naloxone except it is used orally
  • Long duration of activity
  • Single dose block action of heroin effects for 24 hours
  • Used for emergency treatment
  • Once stabilized, give patient naltrexone
  • Patient get no euphoric effect from heroin so person gets off heroin (negative reinforcement)
  • Approved for use by the FDA
  • Also used for treatment of alcohol rehabilitation. 
Last modified: Wednesday, 16 May 2012, 5:11 AM