Can naloxone be used to treat dextromethorphan poisoning and what is the dose?

Naloxone for Dextromethorphan Poisoning

Naloxone can be used to treat dextromethorphan poisoning with respiratory depression, with a recommended dose of 0.04-0.4 mg IV/IM initially, titrating up to 2 mg as needed and repeating every 2-3 minutes until respiratory function improves. 1, 2

Mechanism and Efficacy

• Naloxone has shown effectiveness in antagonizing dextromethorphan toxicity, particularly when respiratory depression is present 3
• While dextromethorphan is not an opioid, it has structural similarities to opioids that may explain naloxone's effectiveness in certain cases
• Naloxone is most effective for the respiratory depression component of dextromethorphan poisoning rather than all toxic effects

Dosing Guidelines

• Initial dose:
  • Adults: 0.2-2 mg IV/IO/IM 1
  • Children: 0.1 mg/kg IV/IO/IM 1
  • Intranasal: 2-4 mg 1
• Titrate to reversal of respiratory depression and restoration of protective airway reflexes
• Repeat every 2-3 minutes as needed if inadequate response 1, 2
• For opioid-dependent patients, use lower initial doses (0.04-0.4 mg) to avoid precipitating severe withdrawal 2

Clinical Decision Algorithm

1. Assessment: Evaluate for signs of dextromethorphan toxicity:

   • Respiratory depression (primary target for naloxone therapy)
   • Altered mental status/sedation
   • Mydriasis (dilated pupils)
   • Tachycardia, hypertension
   • Potential serotonin syndrome with higher doses

2. Treatment approach:

   • For patients with respiratory depression: Administer naloxone as per dosing guidelines above
   • For patients without respiratory depression but with other symptoms: Naloxone may be less effective; focus on supportive care

3. Monitoring after naloxone administration:

   • Monitor for at least 2 hours after the last naloxone dose 2
   • Be prepared to administer additional doses as naloxone's duration (30-45 minutes) may be shorter than dextromethorphan's effects 2

Important Considerations

• Naloxone should be considered for dextromethorphan overdose patients who are sedated or comatose, particularly those with respiratory depression 4

• For severe dextromethorphan poisoning with serotonin syndrome, additional treatments may be needed:

  • Benzodiazepines for seizures
  • External cooling for hyperthermia (>104°F/40°C) 4
  • Consider activated charcoal if presentation is within 1 hour of ingestion 4

• Patients who have ingested >7.5 mg/kg of dextromethorphan should be referred to an emergency department regardless of symptoms 4

Limitations and Caveats

• While naloxone has been reported effective in some cases of dextromethorphan poisoning 3, response may be variable
• Naloxone will not address all aspects of dextromethorphan toxicity, particularly serotonergic effects
• For severe cases with serotonin syndrome, additional treatments like benzodiazepines and supportive care are essential 5
• Patients should be monitored closely as naloxone's duration of action is shorter than many drugs, including dextromethorphan 2
• All patients with intentional abuse or suicidal intent should be referred to an emergency department regardless of symptoms 4