opiate_withdrawal_naltrexone

Mx of severe acute opiate withdrawal due to inappropriate use of naltrexone

introduction

  • naltrexone is a long acting opioid receptor antagonist
  • 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.
  • 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.
  • 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

clinical features of the naltrexone induced opiate withdrawal reaction

  • these are an extreme form of the normal opiate withdrawal features which results in:
    • dysphoria, confusion, hallucinations and agitation +/- reduced GCS
    • severe pains such as muscle, joint and back pains, headache, and abdominal cramping pains
    • profuse diarrhoea and faecal incontinence - yes, the resus room will be a continuous code brown that shift!
    • sympathetic overdrive with tachycardia, hypertension, tachypnoea, sweating, lacrimation, piloerection, yawning, anxiety
    • pupils generally mid-size
    • vomiting may be an issue with risk of aspiration if confused
    • vomiting and diarrhoea may result in hypovolaemia and hypotension

Mx in ED

  • DO NOT GIVE opioids as it would require large doses to overcome the naltrexone and this will risk fatal overdosage
  • may become extremely agitated and possibly violent requiring restraint, heavy sedation, and may require intubation
  • antipsychotic agents such as droperidol (Droleptan) DO NOT SEEM to be useful and there is a report of increased agitation and violence necessitating intubation 1)
  • if clinical picture is not clear, may require CT brain to exclude other pathology
  • usually require Mx in a resuscitation area with 1:1 nursing
  • ABC's as per usual
  • consider iv ketamine boluses and infusion in sub-anaesthetic doses
    • is probably the best analgesic and helps to control the agitation while reducing the sympathetic cardiovascular effects and appears to reduce need for benzodiazepines in subsequent days 2)
    • it is thought that that N-methyl-D-aspartate (NMDA) antagonists such as ketamine attenuate the signs of opiate withdrawal (NMDA blockade presumably outweighs any direct cardiovascular stimulant effects of ketamine) and diminish progression or reverses existing opiate tolerance, and reverse the EEG changes during opiate withdrawal
    • consider 0.3-0.5mg/kg/hr infusion with titrated boluses of 0.2-0.3mg/kg as needed to allow control over iv access
  • iv fluids to rehydrate and replace GIT fluid losses, sweat and provide usual maintenance fluids
  • monitor electrolytes, glucose, fluid balance
  • adjunctive Rx as per usual Mx of opiate withdrawal:
  • most patients will require transfer to HDU or ICU as Mx will need to be prolonged given the duration of action of naltrexone.
2)
Medicina (Kaunas) 2006; 42(8) Effects of ketamine on precipitated opiate withdrawal - placebo-controlled trial of use of 0.5mg/kg/hr ketamine on anesthetised opiate dependent persons given naltrexone to induce acute withdrawal and who were also given clonidine and octreotide
opiate_withdrawal_naltrexone.txt · Last modified: 2014/05/05 04:50 by 127.0.0.1

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