A common drug used to treat alcoholism may also have implications for another kind of addiction: methamphetamine.
Researchers from the University of California – Los Angeles tested the drug, Naltrexone, in 22 men and eight women who used methamphetamine three to four days a week on average. The drug blocks opioid receptors to help reduce the “high” that users experience from alcohol, and in this instance, meth. The study was published in the journal Neuropsychopharmacology.
The participants completed two four-day hospital stays where they were given either Naltrexone (25mg first two days, 50mg third and fourth day) or placebo. Ten days after the first stay, participants were readmitted for the second four-day stay and were given the opposite therapy. On the last day of the cycle, participants were given an intravenous dose of methamphetamine. Researchers evaluated their state three hours after injection.
Overall, Naltrexone significantly reduced participants’ craving for and arousal by methamphetamine. Compared to when using Naltrexone, participants’ heart rates and pulse readings were much higher when given placebo. People taking Naltrexone also had lower heart rates and pulse readings when presented with drug paraphernalia compared to people taking placebo, indicating that the drug reduced the rewarding effects of methamphetamine.
The drug was well-tolerated and had minimal side effects, and was effective in both men and women, although positive effects in men seemed be slightly smaller. The timing of Naltrexone administration (first or second hospital stay) did not affect outcomes.
The researchers, along with support from the National Institute on Drug Abuse and UCLA’s Clinical and Translational Science Institute, are now conducting clinical trials to further evaluate Naltrexone’s effectiveness in people addicted to methamphetamine and test whether higher doses or combinations of the drug with other therapies would be more effective.
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