What is the recommended dose of naloxone (opioid antagonist) for adults?

Recommended Naloxone Dosing for Adults

The recommended initial dose of naloxone for adults with suspected opioid overdose is 0.4 mg to 2 mg administered intravenously, with repeated doses every 2-3 minutes as needed until the desired response is achieved. 1

Dosing by Administration Route

Intravenous (IV) Administration

• Initial dose: 0.4-2 mg 1
• May repeat every 2-3 minutes until adequate response 1
• For postoperative opioid depression, smaller doses of 0.1-0.2 mg are usually sufficient 1
• If no response is observed after a total of 10 mg, question the diagnosis of opioid-induced toxicity 1

Intramuscular (IM) or Subcutaneous (SC) Administration

• Same dosing as IV (0.4-2 mg) if IV access is unavailable 1
• The American Heart Association suggests 2 mg IM repeated in 3-5 minutes if necessary 2
• Supplemental IM doses have been shown to produce a longer-lasting effect 1

Intranasal (IN) Administration

• The American Heart Association recommends 2 mg intranasally, typically repeated in 3-5 minutes if necessary 2
• Nasal bioavailability is approximately 50% with a mean time to maximum concentration of 15-30 minutes 3
• Nasal uptake is likely slower than intramuscular administration 3

Special Considerations

Opioid-Dependent Patients

• Consider using lower initial doses (0.1-0.2 mg) to avoid precipitating severe withdrawal 2
• Withdrawal symptoms may include hypertension, tachycardia, vomiting, agitation, and drug cravings 2
• For patients receiving treatment for severe pain with opioids, high-dose naloxone or rapidly infused naloxone may cause catecholamine release leading to pulmonary edema and cardiac arrhythmias 4

Duration of Action

• Naloxone has a half-life of 30-45 minutes 5
• The duration of action is approximately 2 hours for 1 mg IV 3
• Since naloxone's duration of action may be shorter than the respiratory depressant effects of many opioids, patients should be monitored for recurrent respiratory depression 2
• Repeated doses or continuous infusion may be necessary, especially with long-acting opioids 2

Continuous Infusion

• For continuous infusion, naloxone may be diluted in 0.9% sodium chloride or 5% dextrose 1
• Adding 2 mg of naloxone to 500 mL of solution provides a concentration of 0.004 mg/mL 1
• For pruritus management, a continuous infusion of naloxone at 0.25 mcg/kg/h, titrated up as needed, may be considered 5

Clinical Pearls and Pitfalls

• Naloxone will not reverse respiratory depression due to non-opioid drugs such as benzodiazepines 2
• Standard resuscitative measures should take priority over naloxone administration for patients in cardiac arrest 2
• The goal of treatment is restoration of respiration (not necessarily consciousness) while avoiding severe withdrawal 3
• Initial parenteral doses of 0.4-0.8 mg are usually sufficient to restore breathing after heroin overdose, but fentanyl overdoses likely require higher doses 3
• Most successful overdose reversals (97.6%) involve administration of ≤2 units of naloxone nasal spray 6
• Mixtures for infusion should be used within 24 hours 1

By following these dosing recommendations and considering the patient's opioid tolerance status, clinicians can effectively reverse opioid-induced respiratory depression while minimizing the risk of precipitating withdrawal symptoms.