Researchers from Oxford University say that smokers who take the anti-smoking drug varenicline are three times more likely to quit smoking than those who try to quit without the aid of medication, Reuters reported Jan. 24.

The researchers reviewed six studies sponsored by drug maker Pfizer, including studies that compared the drug to a placebo and to bupropion, an antidepressant sometimes prescribed for smoking prevention. The review revealed that one-year success rates were three times higher among the varenicline used when compared to a placebo group, and 1.6 times higher than the quit rate among bupropion users.

A total of 4,924 smokers took part in the studies.

Varenicline is sold as Chantix in the U.S. and as Champix in Europe.

The research was published online in The Cochrane Library.