Naloxone for the Reversal of Opioid Adverse Effects

Marcia L. Buck, PharmD, FCCP


Pediatr Pharm. 2002;8(8) 

In This Article


Naloxone is administered parenterally. Although it is relatively well absorbed after oral administration, it undergoes extensive first-pass metabolism, making this route of delivery ineffective. After intravenous (IV) administration, naloxone is rapidly distributed throughout the body. It is highly lipophilic and readily crosses into the brain. Onset of action after IV dosing is within 2 minutes, and is only slightly longer with intramuscular (IM), subcutaneous, or endotracheal administration. Duration of action is dependent on route and dose. IV dosing typically provides a duration of action of 20 to 60 minutes. IM use produces a longer effect than IV administration, but absorption from this route is erratic. Naloxone is hepatically metabolized, primarily through conjugation to naloxone-3-glucuronide. The elimination half-life in adults is approximately 60 minutes.[2,3] Elimination is prolonged in neonates, with a half-life ranging from 1.2 to 3.1 hours.[4,5]


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