Naloxone Part 1: The Basics of Naloxone for Opioid Reversal

Leave a comment

October 13, 2015 by dailybolusoflr

By: Anthony J. Busti, MD, PharmD, FNLA, FAHA and Linda Regan MD, FACEP, FAAEM

Note:  Both parts of this topic are being done in collaboration with Dr. Busti’s website, EBM Consult. For additional details about the evidence and references, please click on the hyperlinked articles below.


  • Naloxone (Narcan) is a competitive mu-opioid receptor antagonist.
  • Basic Drug Monograph is available at EBM Consult


  • Onset of Action:  
    • IV or IO = < 2 min
    • Intranasal = 8 – 10 min 
    • Inhalation by neb = 5 min
    • IM, SubQ, or Endotracheal tube =  2 – 5 min
  • Half-life:  ~30 min
  • Duration of Action:  30 – 90 min

Dosing Considerations:

  • If unstable or unclear diagnosis:
    • If NO IV or IO access:  
      • 0.4 – 2 mg IM, SubQ or 0.4 mg via autoinjector (Evizio) if available. Note: usually pre-hospital.  Can repeat up to a max of 10 mg, but if no response then reconsider diagnosis.
        • Neumar RW et al. Circulation 2010;122(suppl):729-67.
      • 2 mg intranasally where 1 mg is placed into each nostril.  Note: delayed onset of action. 
        • Robertson TM et al. Prehosp Emerg Care 2009;13:512-5.
      • Endotracheal tube: not preferred – 0.8 to 5 mg injected down the ET tube followed by 3-4 manual ventilations via BVM.  Note: dose is 2-2.5 times of the IV dose and has unpredictable pharmacokinetics. 
        • Neumar RW et al. Circulation 2010;122(suppl):729-67.
    • If IV or IO access:
      • 0.4 – 2 mg x 1.  Can repeat up to a max of 10 mg, but if no response then reconsider diagnosis.
        • Neumar RW et al. Circulation 2010;122(suppl):729-67.
  • If hemodynamically stable and only respiratory depression:
    • Provide adequate oxygenation and ventilation with manual techniques (placement of supplemental O2, jaw thrust, and/or BVM ventilation) and consider the following to avoid an abrupt reversal that can lead to agitation, N/V and possible non-cardiogenic pulmonary edema:
      • Draw up 1 mg of naloxone into a 10 cc syringe, fill the rest of the syringe with 0.9% NS or SWFI for a total volume of 10 cc in the syringe. This will provide 0.1 mg/cc
      • Give 0.1 cc IV or IO every 30 sec until the desired response is achieved (usually adequate oxygenation and ventilation [as noted on end tidal])
      • Note: there is no evidence proving the above regimen, but is based on expert opinion and experience.  For more information go to EBM Consult
  • Repeat Dosing:
    • Repeat dosing may be needed within 30 – 90 min is concerning for either large opioid or heroin ingestion or the ingestion of a long-acting opioid such as methadone.
      • If after a second dose of naloxone the patient is needing additional naloxone or it becomes known that the patient ingested a long-acting opioid, then start naloxone at 2/3 the effective dose needed to reverse the respiratory depression and give as an IV infusion and admit to the hospital.

Clinical Pearls:

  • Re-dosing naloxone is likely needed within 45 – 90 mins in patients taking long-acting opioids such as:
    • Methadone (half-life ranges from 8 – 59 hrs)
    • Extended-release morphine products (MS Contin, Kadian)
    • Extended release oxycodone (Oxycontin)
  • Methylnaltrexone (Relistor)
    • A SubQ injection that is only FDA approved for opioid-induced constipation not responsive to other bowel stimulants. 
    • It does NOT cross the blood brain barrier and will NOT reverse heroin or opioid overdoses. 
  • Naltrexone (Revia; Vivitrol):
    • Both are FDA approved for treatment of alcohol or opioid dependence. It is comes mainly as an oral dosage form (tablet), which is not recommended, in opioid overdose. 
    • It does come in an IM injection but the half-life is 5 – 10 days as is meant to be used for outpatient management in patients with poor compliance. 
  • Low dose IV infusions of naloxone (0.25 mcg/kg/hr) have been used to reduce itching from opioid use without reversal of pain control.  – Gan TJ et al. Anesthesiology 1997;87(5):1075-81.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: