Nalmefene and naltrexone, the latter of which is available in the United States, are both mu opioid receptor antagonists that also affect the delta opioid receptor. However, nalmefene also is a partial agonist at the kappa opioid receptor.
Dr. Swift said both drugs have been shown in preclinical and clinical studies to interrupt multiple biobehavioral mechanisms responsible for initiating and maintaining alcohol dependence. They reduce alcohol craving, block the motivation to drink to relieve stress and anxiety, and might improve impulsivity.
“Naltrexone has been shown not only to affect the rewards of alcohol consumption, it also seems to have direct cognitive and attentional effects in the orbitofrontal cortex. It reduces preoccupation with alcohol and improves attention to non–alcohol related stimuli,” he said. “I think that’s a really important finding and provides a new understanding of how opioid antagonists work.”
The psychiatrist noted that a recent meta-analysis concluded that opioid antagonists are better for reducing heavy drinking than for increasing abstinence (Addiction 2013;108:275-93).
Dr. Swift reported receiving honoraria from Lundbeck and serving as an adviser or consultant to D&B Pharma and CT San Remo. Dr. van den Brink is on the advisory boards of Lundbeck and more than a half-dozen other pharmaceutical companies.