Naloxone Injectable: Dosing and Precautions

Therapeutic action

Specific opioid antagonist.

Indications

Respiratory depression induced by opioids used for analgesia, anaesthesia, or intoxication.

Forms and strengths, route of administration

Naloxone should be used in addition to assisted ventilation and by well trained personnel.

Closely monitor vital signs, especially respiratory rate, during administration and for at least 12 hours after respiratory function is restored.

• 0.4 mg in 1 ml ampoule (0.4 mg/ml) for IV or IM injection or infusion in 0.9% sodium chloride or 5% glucose.

Dose

IV route is preferred. Use IM route if IV route is not feasible.

• Child: 5 to 10 micrograms/kg by IV injection, repeated if necessary after 2 to 3 minutes until adequate spontaneous ventilation is restored, followed by continuous infusion of 1 to 5 micrograms/kg/hour, or 5 to 10 micrograms/kg by IM injection every 90 minutes.
• Adult: 1 to 3 micrograms/kg by IV injection, repeated if necessary after 2 to 3 minutes until adequate spontaneous ventilation is restored, followed by continuous infusion of 1 to 5 micrograms/kg/hour, or 5 to 10 micrograms/kg by IM injection every 90 minutes.

Duration

The duration of action of naloxone, 20 to 30 minutes by IV route, is shorter than that of opioids, so administration must be maintained for several hours even if breathing improves.

Contra-indications, adverse effects, precautions

• May cause tachycardia, fibrillation, hypertension, pulmonary oedema when given postoperatively due to sudden reversal of analgesia, nausea, vomiting, and acute withdrawal syndrome in opioid-dependent patients.
• Administer with caution and reduce dosage in case of heart failure or coronary artery disease.
• Pregnancy: risks linked to respiratory depression appear greater than risks linked to naloxone.
• Breast-feeding: no contra-indication.
• Naloxone is a specific opioid antidote and cannot be used to antagonise the effects of other drugs producing CNS or respiratory depression.
• Efficacy depends not only on the naloxone dose but also on the dose and potency of the opioid involved.