Naloxone

General medicine context. Source: NALOXONE 400 microgram/ml solution for injection or infusion (UK SPC). Two adult indications are given. (1) Diagnosis and treatment of suspected acute opioid overdose or intoxication: usual starting dose 400-2000 micrograms IV; if the desired degree of reversal and improvement of respiratory function are not attained directly after the IV injection, repeat intravenously at 2-3 minute intervals; may be injected intramuscularly if IV administration is not possible. (2) Complete or partial reversal of CNS depressive effects, especially respiratory depression, caused by natural or synthetic opioids and partial agonist/antagonist opioids: dosage is determined for each patient to obtain optimum respiratory response while maintaining adequate analgesia; an IV injection of 100 to 200 micrograms is usually sufficient, with additional IV injections of 100 micrograms at 2-3 minute intervals if necessary; an additional injection may again be necessary within 1 to 2 hours depending on the type of active substance to be antagonised (short-term effect or slow release), the amount administered, and the time and mode of administration. Naloxone 400 microgram/ml may alternatively be administered as an IV infusion if the duration of action of some opioids is longer than that of the naloxone IV bolus; the infusion rate is determined according to the individual patient, depending on the response to the IV bolus and to the infusion. Duration of action depends on dose and route of administration, varying between 45 minutes and 4 hours. IM onset of action is slower than IV but has a longer action; necessary IM dosages are generally higher than IV dosages and dosage must be adapted to the individual patient. As the duration of action of some opioids may be longer than that of naloxone, the patient must be constantly monitored and repeated doses administered if necessary. Elderly: in patients with pre-existing cardiovascular disease or those receiving potentially cardiotoxic drugs, use with caution, since serious adverse cardiovascular effects such as ventricular tachycardia and fibrillation have occurred in postoperative patients following administration. Neonates whose mothers have received opioids: usual dosage 10 micrograms/kg IV; if respiratory function is not reversed to a satisfactory level, the injection may be repeated at 2-3 minute intervals; if IV is not possible it may be injected IM (initial dose 10 micrograms/kg). The SPC states the dose in neonates can be different due to local recommendations.

Children and adolescents. Suspected acute opioid overdose or intoxication: usual starting dose 10 micrograms/kg IV; if a satisfactory clinical response is not achieved, an increased additional dose of 100 micrograms/kg may be administered; depending on the individual patient an IV infusion may also be necessary; if IV administration is not possible, Naloxone 400 microgram/ml may also be injected IM (initial dose 10 micrograms/kg), divided into several doses. Reversal of opioid-induced CNS depressive effects: initially 10-20 micrograms/kg IV at intervals of 2-3 minutes until satisfactory respiration and consciousness are obtained; additional doses may be necessary at 1- to 2-hour intervals depending on the response of the patient and the dosage and duration of action of the opiate administered. The SPC states the dose in children and adolescents can be different due to local recommendations. Verify against a children's formulary.