Posology : מינונים

4.2   Posology and method of administration

Posology
Complete or partial reversal of CNS and especially respiratory depression, caused by natural or synthetic opioids
Adults
Dosage is determined for each patient in order to obtain optimum respiratory response while maintaining adequate analgesia. An i.v. injection of 0.1 to 0.2 mg naloxone hydrochloride (approx. 1.5-3 μg/kg) is usually sufficient. If necessary, additional i.v. injections of 0.1 mg can be administered at 2 minute intervals until satisfactory respiration and consciousness are obtained. An additional injection can 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 time and mode of administration. Naloxone can alternatively be administered as an i.v. infusion.

Infusion:
The duration of action for some opioids is longer than that of the naloxone hydrochloride i.v. bolus.
Therefore, in situations where depression is known to be induced by such substances or there is a reason to suspect this, naloxone hydrochloride should be administered as a continuous infusion. The infusion rate is determined according to the individual patient, depending on the response of the patient to the i.v. bolus and on the reaction of the patient to the i.v. infusion. The use of the continuous intravenous infusion should be carefully considered and respiratory assistance should be applied if necessary.



Children
Initially, 0.01-0.02 mg naloxone hydrochloride per kg i.v. at intervals of 2-3 minutes until satisfactory respiration and consciousness are obtained. Additional doses may be necessary at 1- to 2-hours intervals depending on the response of the patient and the dosage and duration of action of the opiate administered.

Diagnosis of suspected acute opioid overdose or intoxication
Adults
The initial dose is usually 0.4-2 mg naloxone hydrochloride i.v. If the desired improvement in the respiratory depression is not obtained immediately after i.v. administration, the injections can be repeated at intervals of 2-3 minutes.
Naloxone hydrochloride can also be injected intramuscularly (initial dose usually 0.4-2 mg) if intravenous administration is not possible. If 10 mg naloxone hydrochloride does not produce a significant improvement, this suggests that the depression is wholly or partially caused by other pathological conditions or active substances other than opioids.

Children
The usual starting dose is 0.01 mg naloxone hydrochloride per kg i.v. If the satisfactory clinical response is not achieved, an additional 0.1 mg/kg injection can be administered. Depending on the individual patient, an i.v. infusion may also be necessary. If i.v. administration is not possible, naloxone hydrochloride can also be injected i.m. (initial dose 0.01 mg/kg), divided into several doses.

Reversal of respiratory and other CNS depression in the neonate whose mothers have received opioids
The usual dosage is 0.01 mg naloxone hydrochloride per kg i.v. If the respiratory function is not reversed to a satisfactory level with this dosage, the injection can be repeated at 2 to 3 minute intervals. If i.v.
administration is not possible, naloxone hydrochloride can also be injected i.m. (initial dose 0.01 mg/kg).

Elderly
In elderly patients with pre-existing cardiovascular disease or in those receiving potentially cardiotoxic drugs, naloxone hydrochloride should be used with caution since serious adverse cardiovascular effects such as ventricular tachycardia and fibrillation have occurred in postoperative patients following administration of naloxone hydrochloride.

Method of administration
The medicinal product can be injected intravenously (i.v.) or intramuscularly (i.m.) or can be given via intravenous infusion.

The i.m. administration of naloxone hydrochloride should only be used in cases where an i.v.
administration is not possible.

The most rapid effect is obtained by means of i.v. administration, which is why this method of administration is recommended in acute cases.

When naloxone is administered i.m., it is necessary to remember that the onset of action is slower than following i.v. injection. However, i.m. administration has a longer action than i.v. administration.
The onset of action varies from a half to two minutes after i.v. administration, to three minutes after i.m.
administration.
The duration of action by i.v. is approximately 20 to 30 minutes. By i.m.., it is 2 hours 30 minutes to 3 hours.
It has to be considered that necessary i.m. dosages are generally higher than i.v. dosages and that dosage has to be adapted to the individual patient.

As it is possible that the duration of effect of some opioids (e.g. dextropropoxyphene, dihydrocodeine, methadone) is longer than that of naloxone hydrochloride, the patients must be kept under continuous supervision, and repeated doses must be given if necessary.
For incompatibilities and instructions on dilution of the medicinal product before administration, see section 6.2 and 6.6, respectively.