Naloxone infusion regimen
The role of a naloxone infusion is to maintain the effect of the naloxone bolus regimen after adequate reversal of opioid toxicity has been achieved, thereby preventing recurrence of toxicity. Recurrence of toxicity is more likely in patients who have:
- ingested long-acting opioids (eg methadone)
- ingested modified-release opioid preparations
- ingested synthetic opioids (eg fentanyl analogues)
- impaired renal excretion of active opioid metabolites.
If toxicity recurs after initial response to a naloxone bolus regimen and the patient responds to a further titrated naloxone bolus, consider starting a naloxone infusion. Manage patients with a naloxone infusion in a critical care unit.
The following regimens are indicated for all opioid poisonings, other than buprenorphine poisoning. If a naloxone infusion regimen is required for buprenorphine poisoning, see Buprenorphine poisoning.
If a naloxone infusion is required, in adults, use:
naloxone 4 mg in sodium chloride 0.9% 100 mL by intravenous infusion. Start the infusion at an hourly rate of approximately two-thirds of the total effective bolus dose, then titrate the infusion rate to clinical effect (as recommended below), aiming for a respiratory rate greater than 10 breaths per minute and oxygen saturation greater than 92% on room air. naloxone
If a naloxone infusion is required, in children, use:
naloxone 4 mg in sodium chloride 0.9% 100 mL by intravenous infusion. Start the infusion at an hourly rate of approximately two-thirds of the total effective bolus dose, then titrate the infusion rate to clinical effect (as recommended below), aiming for a normal age-appropriate respiratory rate and oxygen saturation greater than 92% on room air1. naloxone
If the patient experiences opioid withdrawal while on a naloxone infusion, stop the infusion. Monitor the patient for recurrence of toxicity.
Adequate reversal of opioid toxicity is indicated by:
- increased respiratory drive—normal respiratory rate and oxygen saturation greater than 92% on room air
- improved level of consciousness sufficient for the patient to maintain their airway (ie mildly sedated but easily roused).
If toxicity recurs while a patient is on a naloxone infusion, repeat the intravenous naloxone bolus regimen until there is adequate response (up to a total bolus dose of 10 mg), then increase the hourly infusion rate by two-thirds of the total effective supplemental bolus dose of naloxone.
If it is considered that the patient no longer requires naloxone, the infusion should be ceased (rather than titrated down). This should be done in the critical care unit, with close observation and monitoring for 4 hours.
If a prolonged naloxone infusion is required, seek advice from a clinical toxicologist or poisons information centre.