A drug used to treat liver toxicity in Tylenol overdoses may be helpful in treating teens dependent on marijuana, when it is combined with behavioral therapy, according to an expert speaking at the recent American Psychiatric Association annual meeting. The drug is one of a number of new treatments being tested for marijuana dependence, but is the only one so far tested solely in adolescents.

“Young people should be a particular focus of treatment for marijuana dependence,” says researcher Kevin M. Gray, M.D., Associate Professor in the Department of Psychiatry and Behavioral Sciences at the Medical University of South Carolina in Charleston. “We want to treat it early, before a lot of serious outcomes occur when they transition to adulthood.”

His placebo-controlled study of the drug, N-acetylcysteine (NAC), found it was effective when given to teens who were dependent on marijuana. The 116 teens in the study also received weekly, brief skills-based counseling and received compensation for having drug-free urine tests, through an intervention called contingency management, said Dr. Gray, who published the results last year in the American Journal of Psychiatry. He is now setting up a similar study of NAC in marijuana-dependent adults. Both studies are funded by the National Institute on Drug Abuse.

NAC is used to treat a number of other conditions, including cystic fibrosis and other lung ailments, and is considered very safe, Dr. Gray says. It is also sold as a supplement in health food stores.

Treatments for marijuana dependence have not received as much attention as those for other types of substance use disorders, he notes. “There’s a general perception that marijuana may not be as addictive as other drugs, and it’s not seen as a ‘hard’ drug, so people think it’s easy to stop using it,” he says. “The medical marijuana movement has further decreased the view of marijuana as risky. We’re seeing an increased rate of use and dependence in teens, which is especially worrisome because of the increased potency of marijuana in recent years.”

He emphasizes that NAC could be useful as an addition to psychosocial treatment, not a potential stand-alone cure for marijuana dependence. “We haven’t tested NAC alone without counseling, but I suspect it would not be effective by itself,” Dr. Gray states.

Several other potential treatments for marijuana dependence have shown early success in studies. One study published last year found the drug gabapentin, used to treat epilepsy and nerve pain, may help people quit smoking marijuana.

Researchers at Columbia University in New York are studying a synthetic version of THC—the active ingredient in marijuana—called nabilone. They found nabilone decreased marijuana withdrawal symptoms, such as increasing sleep and appetite, and decreased marijuana self-administration, in a laboratory model of relapse. Patients did not experience a “high” from nabilone, indicating it does not have a high abuse potential.