naltrexone drug Written by Kara Rogers Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and... Kara Rogers Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Mar. 26, 2026 •History naltrexone, long-acting opioid receptor antagonist used primarily in the treatment of opioid use disorder and alcohol use disorder. Naltrexone works specifically by blocking opioid receptors in the brain, which disrupts the transmission of signals that produce the euphoric, sedative, and rewarding effects associated with the use of opioid drugs and alcohol. By reducing cravings and limiting the reinforcing effects of these substances, naltrexone has become an important pharmacological tool in addiction treatment and relapse prevention. Naltrexone...

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