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Medication Treatment: Naltrexone

What is Naltrexone (Brand name: Vivitrol)?

  • Naltrexone is an opioid receptor antagonist.
  • Naltrexone blocks opioid receptors in the brain so that if a person takes an opioid such as heroin it won’t have an effect. It can also reduce cravings to use opioids for some people.
    • Naltrexone is also used as a medication treatment for alcohol use disorder, as it has been shown to reduce cravings to use alcohol.  
  • Naltrexone is different from methadone and buprenorphine, because it does not activate (i.e., switch on) the opioid receptors in the brain.
    • Methadone and buprenorphine activate the opioid receptors to a certain degree, which is why they are more effective at reducing withdrawal and cravings.
  • While naltrexone can be a helpful for some individuals, research shows that it is not as effective for more severe opioid use disorders that have affected a person for a long period of time.
  • To take naltrexone an individual has to go 5-7 days opioid free (even longer for some types of opioids) in order to prevent precipitated withdrawal. 
  • Stopping the use of opioids and thus experiencing withdrawal in preparation for starting naltrexone can be extremely difficult, which is one of the reasons it is not the ideal or preferred medication for everyone.

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