BillR wrote :
The simple explanation:
Naltrexone is an FDA approved drug (1984) that was originally intended to treat people suffering from opium (e.g., heroin) addiction. It treated these addictions by blocking the "pleasant" effects from the drug, so addicts who took it did not get "high" anymore.
How does it block the "high?" There are receptors in our brain that an opioid like heroin would use to ...