The successful, but controversial anti-smoking drug varenicline (Chantix) may also help people fight cocaine and alcohol addictions, according to two new studies.
The first study, published this month in the journal Alcohol and Drug Dependence, was a nine-week clinical trial that included 37 people with cocaine addiction. Researchers at the University of Pennsylvania found that participants who took varenicline were half as likely to use cocaine — as measured by urine tests three times a week — as those given placebo. The participants also drank less alcohol while on varenicline. Further, in an experiment in which participants were given a choice between cocaine and money in varying sums, people taking varenicline valued cocaine less than those on placebo, suggesting that the quit-smoking drug made cocaine less rewarding.
The second study, which is forthcoming in Alcoholism: Clinical and Experimental Research, involved 15 moderate to heavy social drinkers. While taking varenicline, they, too, found their drug of choice to be less enjoyable and more unpleasant. This comports with anecdotal reports of smokers who have told researchers that they found alcohol less desirable and therefore drank less while using varenicline to quit smoking.
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Neither study was funded by the pharmaceutical industry and the authors report no conflicts of interest. “A single medication that could decrease the use of both substances would be ideal,” said Hugh Myrick, associate professor of psychiatry at the Medical University of South Carolina and co-author of the drinking study, said in a statement, noting that many people are addicted to both alcohol and cocaine.
But varenicline is not without a downside. Although it has repeatedly been shown to be the most effective pharmacological aid for smoking cessation — in some cases, twice as effective as other medications — it also carries a black box warning from the FDA because of serious psychiatric side effects, including suicidal thoughts and behavior.
One study found that people taking varenicline to quit smoking were eight times more likely to engage in suicidal or self-injuring behavior than those using nicotine-replacement treatments like the patch. Other research has linked varenicline to an increased risk of heart problems in people with pre-existing cardiovascular disease, although the risk-benefit calculation here is complicated by the fact that smoking carries far greater risk to the heart and blood vessels than varenicline.
The drug is unique among anti-addiction medications in the way it affects the brain. Like nicotine, varenicline activates a specific receptor for a neurotransmitter called acetylcholine, but it does so less intensely than the active ingredient of cigarettes does. The net effect is that the drug seems to help by both cutting cravings and making the formerly desired drug less pleasant — without making non-drug pleasures less intense. The most common side effect is nausea.
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While people clearly need to be carefully monitored for psychiatric side effects if they use varenicline, more research is needed to determine whether it can be as helpful in fighting other addictions as it is for quitting smoking and, importantly, whether other medications that act similarly but with fewer side effects can be designed.
Maia Szalavitz is a health writer at TIME.com. Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland’s Facebook page and on Twitter at @TIMEHealthland.