Naloxone is a pure opioid antagonist that acts competitively at opioid receptors. While the mechanism of action of naloxone is not fully understood, the preponderance of evidence suggests that naloxone antagonizes the opioid effects by competing for the same receptor sites, especially the opioid mu receptor. Recently, naloxone has been shown to bind all three opioid receptors (mu, kappa and gamma) but the strongest binding is to the mu receptor.

Naloxone is indicated for the complete or partial reversal of opioid depression, including respiratory depression, induced by natural and synthetic opioids, including propoxyphene, methadone and certain mixed agonist-antagonist analgesics: nalbuphine, pentazocine, butorphanol, and cyclazocine. Naloxone is also indicated for diagnosis of suspected or known acute opioid overdosage. Naloxone may be useful as an adjunctive agent to increase blood pressure in the management of septic shock

Reversal of central depression from opioid use during surgery:

• Adult: 100-200 mcg at intervals of 2-3 minute, titrate dose according to response while maintaining analgesia.
• Child: 5-10 mcg IV at 2-3 min intervals.

Opioid overdosage:

• Adult: 0.4-2 mg repeated if necessary at 2-3 min intervals. If there is no response after a total of 10 mg has been given, consider the possibility of overdosage with other drugs. Reduce dose for opioid-dependent patients: 0.1-0.2 mg. IM/SC routes may be used (at IV doses) if IV admin is not feasible.
• Child: Initially 10 mcg/kg IV followed by 100 mcg/kg IV if necessary. Alternatively, 0.4-0.8 mg IM or SC, repeated as necessary, if IV admin is not feasible.

Opioid-induced depression in neonates due to obstetric analgesia:

• Child: 10 mcg/kg IV, IM or SC repeated at 2-3 min intervals if necessary or 60 mcg/kg as a single IM dose.

Occur secondarily to reversal (withdrawal) of narcotic analgesia and sedation. Mental depression, apathy, inability to concentrate, sleepiness, irritability, anorexia, nausea, and vomiting in high oral doses during initial treatment of opiate addiction.

Patients physically dependent on opioids, or who have received large doses of opioids (acute withdrawal syndrome may be precipitated). Pregnancy and lactation.

Pregnancy & Lactation

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.