naltrexone
n. an opioid antagonist that, like the shorter-acting naloxone (but with better enteral bioavailability), prevents the binding of opioid agonists to opioid receptors. Accordingly, both drugs may precipitate a rapid withdrawal syndrome. If naltrexone is taken prior to use of opiate drugs, it will prevent their reinforcing effects and can therefore be used for the management of opioid dependence in individuals desiring abstinence. Naltrexone is also appropriate as an adjunctive treatment in the management of alcoholism, either in oral or in long-term injectable formulations. The long-term injectable is also approved for opioid dependence. U.S. trade name: ReVia; Vivitrol.