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  • naltrexone is a long acting opioid receptor antagonist used in addiction medicine
  • it should NOT be used in opiate-dependent persons within 7-10 days of last opiate dose otherwise there is a high risk of a severe, potentially life threatening acute opiate withdrawal reaction.
  • severe acute withdrawal reactions usually occur in the context of a IV heroin user accessing naltrexone and using it inappropriately or inadvertently while still using heroin - see Mx of severe acute opiate withdrawal due to inappropriate use of naltrexone
  • naltrexone has also been used to provide Ultrarapid Opioid Detoxification (UROD), but this is a controversial procedure which exposes the patient to risks of general anaesthesia and acute severe withdrawal features without clear benefits


  • peak plasma levels of naltrexone occur at ~3hrs after oral dose
  • naltrexone has a half-life of ~4hrs but an active metabolite has a half-life of ~16 hrs, thus opioid receptor blockade and the withdrawal reaction usually lasts 24-72hrs and may require HDU Mx or even ICU if intubation is required.

usual dosage

  • in Australia, naltrexone use is restricted to specialist clinics
  • adult dose:
    • 25 mg o daily, increasing to 50 mg
    • courses of treatment generally last many months
naltrexone.txt · Last modified: 2014/05/05 04:51 by

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