Group: opioid antagonist
Injection: 0.4 mg (hydrochloride) in 1-ml ampoule
Naloxone is a semisynthetic opioid antagonist that competes with opioid analgesics for specific receptor sites in the central nervous system. Its effect, which persists for about 45 minutes, occurs within 1-2 minutes of intravenous administration.
To counteract respiratory depression induced by opioids administered during anaesthesia or by opioid overdosage.
Preventing opioid abuse
Naloxone is poorly absorbed when taken by mouth, so it is commonly combined with a number of oral opioid preparations, including buprenorphine and pentazocine, so that when taken orally, just the opioid has an effect, but if misused by injecting, the naloxone blocks the effect of the opioid. This combination is used in an effort to prevent abuse. In Germany, tilidine is sold in a fixed combination with naloxone.
Naloxone can be used on infants who were exposed to intrauterine opiates administered to mothers during delivery. However, there is insufficient evidence for the use of naloxone to lower cardio-respiratory and neurological depression in these infants. Infants exposed to high concentrations of opiates during pregnancy may have CNS damage in the setting of perinatal asphyxia. Naloxone has been studied to improve outcomes in this population, however the evidence is currently weak.
In people with shock, including septic, cardiogenic, hemorrhagic, or spinal shock, those who received naloxone had improved blood flow. The importance of this is unclear.
Naloxone is also experimentally used in the treatment for congenital insensitivity to pain with anhidrosis, an extremely rare disorder (one in 125 million) that renders one unable to feel pain or differentiate temperatures.
Naloxone can also be used as an antidote in overdose of clonidine, a medication that lowers blood pressure.
Naloxone can also be used to treat itchiness brought on by opioid use
Dosage and administration
Adults: 100-400 micrograms i.v. titrated to the needs of the patient and repeated, as necessary, at intervals of 2-3 minutes.
Children: 5-10 micrograms/kg i.v. repeated as above.
Neonates: 10 micrograms/kg i.v., i.m. or subcutaneously immediately after birth.
Adults: 200 micrograms i.v. repeated, as necessary, at 2-minute intervals to a maximum of 10 mg.
Dosage should be reduced in patients with cardiovascular conditions predisposing to dysrhythmias.
• Known hypersensitivity to naloxone.
• Physical dependence on narcotics (naloxone will precipitate an acute withdrawal syndrome in dependent patients).
The use of naloxone to counteract respiratory depression complements other resuscitative measures including maintenance of a clear airway, control of ventilation, cardiac massage, maintenance of an effective circulatory volume and vasopressor therapy. The necessary facilities and equipment for such treatment must be immediately available.
Use in pregnancy
Naloxone should be used during pre-term pregnancy only when the need outweighs any possible risk to the fetus.
Unnecessarily high doses may cause hypertension and tachycardia. Transient nausea, vomiting, sweating, tachycardia, hypertension and tremor have been reported. Seizures are rare.
Patients with pre-existing cardiovascular disease have occasionally developed ventricular dysrhythmias.
Naloxone injection should be kept protected from light.