A new study has found that bupropion (Zyban), an antidepressant, increases the odds of success for people who are trying to stop smoking. The U.S. Food and Drug Administration recently approved the use of bupropion as an aid in smoking cessation.

The report was published in the Oct. 23, 1997, issue of the New England Journal of Medicine. The 615 participants who began the study were divided into four groups: One group received a placebo while the other groups received daily bupropion doses of either 100, 150, or 300 milligrams (mg) for 7 weeks. All participants received similar, brief stop-smoking counseling several times during the treatment phase. Reports of abstinence were confirmed by checking carbon monoxide levels in the participants' breath.

At the end of the 7-week treatment period, 19 percent of those taking placebos were abstinent from smoking. The abstinence rate for the 300-mg group was 44.2 percent, the 150-mg group attained 38.6 percent abstinence, and the 100-mg group had 28.8 percent abstinence. By the end of the year, the abstinence rates were 12.4 percent for the placebo group, 23.1 percent for the 300-mg group, 22.9 percent for the 150-mg group and 19.6 percent for the 100-mg group.

The study was conducted by researchers at three institutions: Mayo Clinic, Rochester, Minn.; Palo Alto Center for Pulmonary Disease Prevention, California, and West Virginia University, Morgantown.

Mayo Health Oasis interviewed Richard D. Hurt, M.D., lead author of the study and director of Mayo Clinic's Nicotine Dependence Center, to discuss the results.

Oasis: Overall, what does the study tell you about bupropion as a smoking-cessation medication?

Dr. Hurt: Bupropion is the first non-nicotine product that works, but it is not a magic bullet. Smokers who are interested in stopping smoking have a better chance with bupropion than with a placebo. We also found that the higher doses work better than the lower dose, and that the higher dose decreases the weight gain that often occurs when a smoker stops smoking.

Oasis: Why is an antidepressant of interest to smoking-cessation researchers?

Dr. Hurt: Smokers are more likely to have a history of major depression than nonsmokers, and nicotine may act as an antidepressant in some smokers. The development of depression after a person stops smoking may lead to smoking relapse, so it was theorized that an antidepressant may help counteract the loss of nicotine's effects. Of the antidepressants studied so far, bupropion is the first shown to have efficacy in smoking cessation.

Oasis: The abstinence rates among the 150- and 300-mg groups were quite high at the end of the 7-week treatment period, but had dropped by the end of the year. Would treatment with bupropion for longer than 7 weeks help maintain the higher abstinence rate?

Dr. Hurt: The abstinence rate at the end of the year was still significantly higher for the 150- and 300-mg groups than for the placebo and 100-mg groups, even though it had dropped from the 7-week levels. The first step was finding out if bupropion works, and we found that it does. It seems likely that a longer treatment period might help some people, thus the labeling of the drug for smoking cessation recommends a treatment period of 6 to 12 weeks. Antidepressants are commonly used for longer periods to treat depression. They have almost no abuse potential. But we weren't looking at long-term use in this study on smoking cessation. We wanted to see if it worked at all. This study evaluated a short treatment period similar to those used for nicotine-patch studies.

Oasis: How do your results compare to nicotine-patch studies?

Dr. Hurt: Favorably. The success rates at the end of treatment and at 1 year are similar.

Oasis: Were there any surprises in your findings?

Dr. Hurt: Yes, besides finding out that bupropion works for smoking cessation, we discovered that at the higher dose, 300 mg, there was less weight gain than at the other doses or with the placebo for those who stopped smoking.

Oasis: So bupropion seems to help people stop smoking and also gain less weight?

Dr. Hurt: Yes. That's an important factor in smoking cessation. People who stop smoking typically gain weight — usually about 5 pounds. The fear of gaining weight keeps some people, particularly women, from even trying to quit. So a medication that can help you stop smoking and also decrease weight gain would offer an advantage.

Oasis: Were there any significant side effects or safety concerns?

Dr. Hurt: Side effects were fairly minimal. The most frequent were insomnia and dry mouth. Antidepressants in general are associated with a small risk of seizure. We used a newer, sustained-release form of bupropion that can be taken twice a day instead of three or four times. It's also thought to have a lower likelihood of causing seizures because it doesn't have the high peaks and troughs that a more immediate-release form does.

Oasis: Did anyone in your study have a seizure?

Dr. Hurt: No one had a seizure. However, we excluded from the study anyone who had a personal or family history of seizure, a history of severe head trauma, eating disorders, or active alcoholism. Doctors should screen for the possibility of seizures before starting treatment with bupropion.

Oasis: Did bupropion affect nicotine withdrawal symptoms?

Dr. Hurt: We didn't see any difference across the groups in frequency or severity of withdrawal symptoms.