The Antagonist Blockade
Naltrexone is a full opioid antagonist. It binds to the mu-opioid receptors with high affinity but does not activate them at all. Instead, it forms a physical blockade. If a person takes opioids while on naltrexone, the opioid molecules cannot bind to the receptors, resulting in absolutely no euphoric or analgesic effects.
Efficacy in Alcohol Use Disorder
Naltrexone is also highly effective for alcohol use disorder. It blocks the endorphin receptors that trigger the pleasurable sensations of drinking, thereby reducing cravings and helping patients maintain abstinence.