Naloxone

Indication

• Naloxone is indicated for the reversal of severe respiratory depression that is caused by narcotics. It is effective against natural (E.G. morphine) and synthetic (E.G. meperidine, fentanyl) narcotics; it is not effective against barbiturates, tranquilizers, non-narcotic anaesthetics or sedatives
• Naloxone has also been studied experimentally in the treatment of septic shock

Pharmacology

• Naloxone is essentially a pure opiate antagonist with little or no agonist (morphine-like) activity
• metabolized primarily in the liver
• Rapidly inactivated following oral administration, therefore very large doses are required if naloxone is given orally
• onset of action; IV: 1 to 2 minutes SC,IM: 2 to 5 minutes
• Naloxone's duration of action is 45 minutes to 4 hours; this is usually shorter than that of the narcotic. Thus, the effects of the narcotic may return as the effects of naloxone wear off, and repeated doses of naloxone may be required

Side Effects

• Abrupt reversal of narcotic depression may result in vomiting, sweating, tachycardia, hypertension, tremors, agitation and irritability

Precautions

• Infants must be kept under continuous surveillance
• Monitor respiratory rate, blood pressure, signs of irritability/agitation
• Note that repeated doses of naloxone may be required (see Pharmacology)

Dose

• Reversal of Narcotic Depression
  • 0.1 mg/kg: IV push over 30 seconds; IM, SC or intratracheal
  • May be given every 2 to 3 minutes until the effects of the narcotic are reversed
  • may need to repeat every 1 to 2 hours

Special Indication

• Ultra low dose (0.1 mcg/kg/h) naloxone has been used with very high doses of opioid infusions to minimize the development of tolerance
• this is currently experimental and has NOT been studied in neonates
• Ultra low dose naloxone infusion is weaned over 3 days (50 % of initial rate X 2 days, 25 % of initial rate X 1 day, stop on Day 4) once the opioid infusion starts to decrease

Supplied As

• 0.4 mg/mL, 1 mL ampoule