Nalmefene (brand names Opvee, Zurnai, Revex) is an opioid receptor antagonist medication used primarily to treat acute opioid overdose and, in some regions, to help manage alcohol dependence.
It works by blocking opioid receptors in the brain.
Nalmefene has two primary clinical applications:
Opioid overdose approved for emergency use to reverse the effects of known or suspected opioid overdose, including life-threatening respiratory depression and sedation.
Its longer duration of action compared to naloxone is a key feature, which may be beneficial with longer-acting or synthetic opioids like fentanyl.
Alcohol Dependence: oral tablets of nalmefene are approved to help adults reduce alcohol consumption on an “as-needed” basis, particularly for those with a high drinking risk level who do not require immediate detoxification.
It reduces the reinforcing and rewarding effects of alcohol, which helps curb cravings and overall intake.
It is available in various forms, including: Intranasal spray. Auto-injector for intramuscular or subcutaneous injection Injectable solution for intravenous, intramuscular, or subcutaneous administration Oral tablets (used in Europe)
Nalmefene is a prescription-only medication.
As an opioid antagonist, administering nalmefene to a person who is physically dependent on opioids can cause sudden, severe withdrawal symptoms such as body aches, fever, sweating, anxiety, and gastrointestinal issues.
It has a significantly longer half-life (around 11 hours) than naloxone (60-90 minutes).
This extended action helps maintain the reversal effect but necessitates continued medical monitoring in an overdose situation, as the effects of the opioid may still outlast a single dose of the antagonist.
Unlike naltrexone, nalmefene has not been linked to clinically apparent liver injury.
Nalmefene is not an opioid agonist and has no abuse potential, so it is not a controlled substance.