Naloxone, sold under the brand names Narcan (4 mg) and Kloxxado (8 mg) among others, is a medication used to reverse the effects of opioids. It is commonly used to counter decreased breathing in opioid overdose. Effects begin within two minutes when given intravenously, and within five minutes  when injected into a muscle. The medicine can also be administered by spraying it into a persons nose. Naloxone commonly blocks the effects of opioids for 30 to 90 minutes. Multiple doses may be required, as the duration of action of some opioids is greater than that of naloxone.Administration to opioid-dependent individuals may cause symptoms of opioid withdrawal, including restlessness, agitation, nausea, vomiting, a fast heart rate, and sweating. To prevent this, small doses every few minutes can be given until the desired effect is reached. In those with previous heart disease or taking medications that negatively affect the heart, further heart problems have occurred. It appears to be safe in pregnancy, after having been given to a limited number of women. Naloxone is a non-selective and competitive opioid receptor antagonist. It works by reversing the depression of the central nervous system and respiratory system caused by opioids. Naloxone generally has no effect on those not using opioids, has no abuse potential, and is recommended by the World Health Organization for distribution to anyone likely to encounter a fatal opioid overdose, including emergency personnel and friends and family members of those using opioids.
This combination is used in an effort to prevent non-medical use. Other uses
Naloxone can be used to treat opioid induced itchiness and constipation.A 2003 meta-analysis of existing research showed naloxone to improve blood flow in patients with shock, including septic, cardiogenic, hemorrhagic, or spinal shock, but could not determine if this reduced patient deaths.Naloxone has been used experimentally in the treatment of congenital insensitivity to pain with anhidrosis. Special populations
Pregnancy and breastfeeding
Naloxone is pregnancy category B or C in the United States. Studies in rodents given a daily maximum dose of 10 mg naloxone showed no harmful effects to the fetus, although human studies are lacking and the drug does cross the placenta, which may lead to the precipitation of withdrawal in the fetus. In this setting, further research is needed before safety can be assured, so naloxone should be used during pregnancy only if it is a medical necessity.Whether naloxone is excreted in breast milk is unknown, however, it is not orally bioavailable and therefore is unlikely to affect a breastfeeding infant. Children
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 cardiorespiratory 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.