Naloxone

This opioid antagonist is a useful adjunct in the management of opioid intoxication, particularly if there is CNS or respiratory depression. Caution is advised in those who are opiate-dependant and naloxone should only be used if there is significant CNS (GCS <12) and respiratory depression (RR <8). In these patients titrate slowly so as not to precipitate an acute withdrawal

Administration

• Initial dose = 100 micrograms IV or 400 micrograms IM or SC.
• Titrate dose of 100 micrograms IV every 30-60 seconds.
• Paediatric dose = usually can be given in excess as they are unlikely to have opiate dependance. APLS quotes 10 microgram/kg to a maximum of 800 micrograms
• Re-sedation can occur within 2 hours
• Partial opioid antagonists, or controlled-release morphine, oxycodone or methadone can result in higher doses of naloxone and also infusions. Infusions are started at 2/3rd of the initial dose required in the first 1 hour. 100 microgram/hour can be made up of a 2 mg naloxone vial diluted in 100 ml of 0.9% saline and running at 5 ml/hour
• All patients given naloxone should be observed for re-sedation for at least 2 hours after the last dose.

References

• Clarke SFJ, Dargan PI and Jones AL.  Naloxone in opioid poisoning: walking the tightrope.  Emergency  Medicine Journal 2005; 22:612-616.
• Ashton H, Hassan Z. Best evidence topic report. Intranasal naloxone in suspected opioid overdose. Emergency Medicine Journal 2006; 23:221-223.