Illegal use of opioids such as heroin, fentanyl, and morphine can lead to addiction and impaired quality of life. Several lines of evidence suggest that naltrexone can treat addiction to opioids by blocking certain signals in the brain:
In opioid-addicted patients recently undergoing detoxification, naltrexone implant is more effective than oral naltrexone treatment at preventing relapse.
Studies found that one 50-mg tablet blocks μ-opioid receptors for 24 to 36 hours, preventing relapse and symptoms of withdrawal.
A study found that sustained-release injected naltrexone in patients with opioid dependence is associated with significantly better outcomes.