Final answer:
Many heroin-addicted people prescribed naltrexone stop taking it because it blocks the effects of opioids, leading to discomfort and cravings for the drug.
Step-by-step explanation:
Many heroin-addicted people prescribed naltrexone stop taking it because it blocks the effects of opioids, which can lead to discomfort and cravings for the drug.
Naltrexone works as an opioid antagonist, binding to opioid receptors in the brain and preventing the euphoric effects of heroin or other opioids.
Since naltrexone does not provide the pleasurable sensations heroin users seek, they may be less motivated to continue taking it.