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| Naltrexone-attenuated cue-induced craving for methamphetamine (MA) as compared with placebo. Graphic: Courtesy of Dr. Lara Ray |
UCLA researchers have found that a drug to treat alcoholism, Naltrexone, may also have promise for the treatment of addiction to methamphetamine. “The results were about as good as you could hope for,” says Lara Ray, PhD, director of the UCLA Addictions Laboratory and a member of the UCLA Brain Research Institute.
The study was the first in the U.S. to evaluate Naltrexone for treating methamphetamine addiction. During a four-day hospital stay, each of the 22 men and eight women in the study were given either Naltrexone or a placebo daily. Ten days later, the subjects were readmitted to the hospital for four more days; those who had taken Naltrexone earlier were given placebos, and vice versa. On the last day of each hospital visit, all participants were given intravenous doses of methamphetamine. Three hours later, the researchers asked how they felt and how much they wanted more of the drug.
The scientists found that Naltrexone significantly reduced the subjects’ craving for methamphetamine and that it made them less aroused by methamphetamine. In addition, participants taking Naltrexone had lower heart rates and pulses when they were presented with their drug paraphernalia than those who were given placebos.
Dr. Ray says the results indicated that Naltrexone reduced the rewarding effects of the drug. Naltrexone was well-tolerated and had very minimal side effects. The researchers found that men and women both were helped, although the positive effect on men was slightly smaller. It made no difference whether or not the participants were given Naltrexone during their first or second hospital stay.
Naltrexone works by blocking opioid receptors in the brain. Dr. Ray says that in previous studies, people undergoing treatment for alcoholism reported getting less of a “high” from drinking when they take Naltrexone. Dr. Ray, whose research team studies the causes of drug and alcohol addiction and possible treatments, plans to examine whether or not Naltrexone would be more effective in combination with other pharmaceuticals and at different doses.
Although the new study is promising, it needs to be backed up by clinical trials, Dr. Ray says. The next step in evaluating Naltrexone’s effectiveness for treating people addicted to methamphetamine is already underway with clinical trials sponsored by the National Institute on Drug Abuse.
“The Effects of Naltrexone on Subjective Response to Methamphetamine in a Clinical Sample: A Double-blind, Placebo-controlled Laboratory Study,” Neuropharmacology, April 15, 2015
