Naloksone

Naloksone, often spelled naloxone, is a medication used to rapidly reverse the effects of opioid overdoses. It is an opioid receptor antagonist that can restore breathing in people who have overdosed on opioids such as heroin, fentanyl, or prescription painkillers. It is widely available in injectable forms and as an intranasal spray and is marketed under several brand names, including Narcan and Evzio.

Naloxone works by binding to mu, kappa, and delta opioid receptors with higher affinity than most opioids, displacing them from the receptors and thereby reversing opioid-induced central nervous system and respiratory depression. Its effects begin within minutes after administration, making it a critical intervention in emergencies. However, its duration of action can be shorter than that of some opioids, which can lead to re-narcotization if the person is not monitored and additional care is provided.

In medical practice, naloxone is used in suspected opioid overdoses in emergency settings, by first responders, and in some community theses where take-home kits are distributed. Dosing varies by route: typical initial intravenous or intramuscular doses around 0.4 mg, with intranasal formulations delivering about 2 mg per spray; repeated dosing may be necessary depending on the amount and type of opioid involved and the patient’s response. Patients should be monitored and transported to a medical facility, as recurrence of overdose symptoms can occur.

Safety considerations include the potential for acute withdrawal symptoms in opioid-dependent individuals, which can include agitation, nausea, vomiting, sweating, and increased heart rate. Naloxone is listed on the World Health Organization’s essential medicines list and is widely regarded as a safe, life-saving antidote when used appropriately.