Naloxone

Naloxone is a crucial emergency medication used in pediatrics to rapidly reverse opioid overdose and opioid-induced respiratory depression. It acts as a competitive opioid receptor antagonist, primarily at μ-opioid receptors.

• Generic Name: Naloxone
• Brand Names: Narcan, Evzio
• Drug Class: Opioid antagonist
• Available Forms: Injectable solution, nasal spray

Mechanism of Action

Naloxone works by:

• Competitively binding to opioid receptors, particularly μ-opioid receptors
• Displacing opioid agonists from these receptors
• Rapidly reversing the central nervous system and respiratory depressant effects of opioids
• Having a higher affinity for opioid receptors than most opioids, allowing it to effectively reverse their effects

Indications

In pediatric emergency medicine, naloxone is primarily used for:

• Complete or partial reversal of opioid-induced respiratory depression
• Treatment of acute opioid overdose
• Reversal of opioid-induced central nervous system depression
• Diagnosis of suspected acute opioid overdose
• Management of opioid-induced pruritus (off-label use)

Dosage and Administration

Dosing in pediatrics varies based on the clinical situation and route of administration:

• For known or suspected opioid overdose:
  • Intravenous/Intramuscular/Subcutaneous: 0.1 mg/kg/dose (maximum: 2 mg/dose)
  • Intranasal: 2-4 mg/dose as a single spray
• For reversal of therapeutic opioid-induced respiratory depression:
  • Initial dose: 0.001-0.005 mg/kg/dose IV, titrated to effect
  • May repeat every 2-3 minutes if needed
• Continuous IV infusion (if repeated doses are required):
  • 0.004-0.16 mg/kg/hour, adjusted based on response

Adverse Effects

While generally safe, naloxone can cause:

• Acute opioid withdrawal syndrome in opioid-dependent patients
• Nausea and vomiting
• Agitation or irritability
• Tachycardia
• Hypertension
• Pulmonary edema (rare)
• Seizures (rare, usually associated with underlying pathology)

Precautions and Considerations

• Short half-life: Naloxone's duration of action is typically shorter than that of many opioids, necessitating close monitoring for re-sedation
• Dose-dependent reversal: Lower doses may reverse respiratory depression while maintaining some analgesia
• Opioid-dependent patients: Use caution to avoid precipitating acute withdrawal
• Partial agonists/antagonists: Naloxone may be less effective in reversing the effects of buprenorphine or pentazocine
• Cardiovascular effects: Monitor for potential tachycardia or hypertension, especially in cardiac patients
• Neonates: Use with caution in neonates of opioid-dependent mothers to avoid withdrawal