Drug May Help Women Stop Smoking

Adding the opiate blocker naltrexone to the combination of behavioral therapy and nicotine patches boosted smoking cessation rates for women by almost 50 percent when assessed after eight weeks of treatment, but made no difference for men, report researchers from the University of Chicago in the October 2006 issue of the journal Nicotine and Tobacco Research.

Naltrexone helped reduce the craving for cigarettes and lessened the discomforts of withdrawal for women in the study. It also reduced the weight gain often experienced by men and women in the first month after quitting.

"Women have historically had less success than men in giving up cigarettes," said study author Andrea King, Ph.D., associate professor of psychiatry at the University of Chicago. "In this small study, naltrexone seems to have closed that gap."

The researchers studied 110 nicotine-dependent smokers who wanted to quit. The participants, on average, had smoked about a pack a day for 25 years and had already tried to stop multiple times.

All volunteers received standard comprehensive smoking cessation treatment, including one-hour behavioral counseling sessions once a week, beginning two weeks before their quit date and lasting until four weeks after, and nicotine patches for the first month after quitting.

Half of the participants also received 50 milligrams per day of oral naltrexone, beginning three days prior to the quit date and continuing for eight weeks afterwards. The other half received identical pills that contained no medication. Neither the patients nor the researchers knew who received the drug.

Because naltrexone works by blocking some of the effects of narcotics, such as morphine, it was originally used to treat heroin addicts. It also helps reduce relapse rates in alcoholics. Scientists suspect that it inhibits the chemical signals within the brain that convey pleasure when people use drugs such as alcohol or nicotine. When the immediate rewards of drinking or smoking are blocked, people report reduced craving for alcohol or cigarettes.

In this study, success was defined as "not smoking (even one puff) daily for one week and not smoking even a puff at least one day in each of two consecutive weeks at any point in the trial." A more stringent criterion of prolonged abstinence, not smoking even one puff after the first week of quitting, was also used and showed similar results.

Fifty-two research subjects received naltrexone. In this group, after eight weeks of treatment, men and women had comparable success rates: 62 percent of men and 58 percent of women. In contrast, among the 58 research subjects who did not receive naltrexone, success remained high in men with 67 percent quitting smoking, but was significantly lower in women, with only 39 percent quitting. So, while the women on placebo had lower quit rates than men, the women taking naltrexone had quit rates similar to men.