What is the standard dose of Narcan (naloxone) for reversing opioid overdose?

Standard Dosing of Naloxone (Narcan) for Opioid Overdose Reversal

The standard dose of naloxone for opioid overdose is 0.4 mg to 2 mg intravenously, which may be repeated every 2-3 minutes if needed until respiratory function improves. 1, 2

Adult Dosing by Route of Administration

Intravenous (IV) Administration

• Initial dose: 0.4 mg to 2 mg 1, 2
• May repeat every 2-3 minutes if inadequate response 1, 2
• Continue until respiratory function improves or up to 10 mg total 1, 2
• For post-operative opioid depression: Use smaller doses of 0.1 to 0.2 mg IV increments 1, 2

Intramuscular (IM) or Subcutaneous (SC) Administration

• Same dosing as IV (0.4-2 mg) if IV access is unavailable 1, 2
• May need to repeat doses due to slower absorption compared to IV route

Intranasal (IN) Administration

• Standard dose: 2 mg (typically as 2 mg/mL concentration) 3, 4
• Higher concentration intranasal naloxone (2 mg/mL) has similar efficacy to IM administration 4
• May need to repeat dosing every 2-3 minutes if inadequate response 5
• Multiple doses are often necessary, with 78% of overdose reversals requiring ≥2 doses in real-world settings 6

Pediatric Dosing

Children

• Initial dose: 0.01 mg/kg IV 1, 2
• If inadequate response, may give subsequent dose of 0.1 mg/kg 1, 2
• For children <5 years or <20 kg: 0.1 mg/kg 3
• For children ≥5 years or ≥20 kg: 2 mg 3

Neonates

• Usual initial dose: 0.01 mg/kg body weight IV, IM, or SC 1, 2

Important Clinical Considerations

Duration of Action

• Naloxone's duration of action is approximately 30-45 minutes 5, 7
• This is shorter than many opioids, especially long-acting formulations 3, 5
• Patients must be observed for at least 2 hours after the last dose of naloxone 5
• For long-acting opioid overdoses, longer observation periods are required 3, 5

Potential Adverse Effects

• May precipitate acute withdrawal in opioid-dependent individuals 3
• To minimize withdrawal symptoms, consider starting with lower doses (0.04-0.4 mg) in suspected opioid-dependent patients 3
• Withdrawal symptoms may include agitation, hypertension, tachycardia, vomiting 3

Clinical Pitfalls to Avoid

1. Inadequate dosing when dealing with potent synthetic opioids like fentanyl 5, 6
2. Premature discharge after naloxone response without adequate observation 5
3. Focusing on awakening rather than adequate ventilation 5
4. Assuming one dose will be sufficient - multiple doses are often required 6, 8
5. Delaying assisted ventilation while administering naloxone 3, 5

Algorithm for Naloxone Administration in Suspected Opioid Overdose

1. Assess responsiveness and breathing
2. If unresponsive with abnormal breathing:
   • Begin rescue breathing
   • Administer naloxone:
     • IV/IM/SC: 0.4-2 mg in adults
     • IN: 2 mg (2 mg/mL concentration)
     • Pediatric: 0.01 mg/kg initially, may increase to 0.1 mg/kg if needed
3. Reassess after 2-3 minutes
4. If inadequate response, repeat naloxone dose
5. Continue monitoring for at least 2 hours after last dose
6. For long-acting opioid overdoses, extended monitoring is required

Recent evidence suggests that in the era of potent synthetic opioids, multiple naloxone administrations are increasingly common, with studies showing 9% of patients requiring two or more doses 8 and 78% of community reversals using multiple doses 6.