Extended use of bupropion, an antidepressant, may help people quit smoking, according to a new study.

Bupropion is sold as Wellbutrin and Zyban, and the key may lie in smokers taking it for longer periods of time before stopping smoking. In the study, done by University at Buffalo researchers, one group of subjects received three weeks of a placebo; the other group received three weeks of bupropion; and everyone received bupropion after that. All of the subjects also received smoking cessation counseling.

“One of the things I love about this type of study is that everybody gets a good treatment,” said Larry Hawk, Ph.D., a university psychologist, whose father died from a smoking-related cancer. “Our control group is getting standard effective therapy. One of the reasons that’s important to me is people often come in with several failed attempts to quit. These treatments give them a sense that this time they’ll be more successful — before they get to their quit day.”

Those who had extended use of bupropion prior to quitting had less craving or withdrawal. More than half of those in the extended group remained smoke-free a month after quitting, compared to 31% of those in the standard treatment group.

Results appear in Nicotine & Tobacco Research.