A narcotic antagonist, works by blocking opioid receptors in the brain, without activating them, therefore, blocking the effects of opioids (e.g., heroin, morphine). Naltrexone has a High affinity to the Mu receptor, yet not as high as buprenorphine. Naltrexone was first synthesized in 1965. It was approved by the FDA in 1984 for preventing relapse in opioid addicted patients. Later in 1994 the FDA approved it to treat alcoholism, it tends to reduce cravings for alcohol. Naltrexone binds to the opioid receptors stronger then other opioids (except buprenorphine) this results in near complete blocking of opioids. Naltrexone is not used extensively because the retention rate of patients is very low. Unlike buprenorphine Naltrexone does not activate the opioid receptors at all, so any lingering withdrawal, or pain from a compromised endogenous opioid system will still exist.
To suppress the debilitating symptoms of cravings and withdrawal, enabling the patient to engage in therapy, counseling and support, so they can implement positive long-term changes in their lives which develops into the new healthy patterns of behavior necessary to achieve sustained addiction remission. - explain -