Evidence suggests women have a reduced response to nicotine replacement and other traditional treatments which is why more targeted pharmacotherapy and intervention strategies may be necessary to improve their quit rates. Opioid antagonist naltrexone is proving to be an effective adjunctive pharmacotherapy approach for female smokers.

In a randomized clinical trial 110 adult male and female nicotine-dependent smokers, who expressed interest in quitting smoking, were given a treatment of 50 mg daily oral naltrexone vs. placebo in conjunction with counseling and standard smoking cessation treatment (1 month of the nicotine patch). Treatment lasted for eight weeks.

At the end of the treatment, the results seemed disappointing as the naltrexone group did not have significantly better quit rates compared to the placebo group (48% quit on naltrexone vs. 41% on placebo). However, when comparing results for men and women separately; adding the opiate blocker naltrexone to the combination of behavioral therapy and nicotine patches boosted smoking cessation rates for women by almost 50 percent (39% quit rate in placebo group vs. 58% in naltrexone group) but made no significant difference in quitting for men. In addition the study also revealed that naltrexone significantly reduced men's and women's smoking cessation related weight gain.

Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol and opioid dependence. Naltrexone should not be confused with naloxone, which is used in emergency cases of opioid overdose. Naltrexone is used in longer-term dependence control by blocking receptors and preventing the high associated with the use of these substances. It can only be used after the initial detoxification period. It should not be combined with opiate drugs as it will induce withdrawal symptoms rather than diminish them.

"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."

Sources: Drug May Help Women Stop Smoking (Newswise), Efficacy of Naltrexone in Women's Smoking Cessation (Clinicaltrials.gov), Opiate Blocker Naltrexone May Help Women Stop Smoking (About.com), Naltrexone alteration of acute smoking response in nicotine-dependent subjects (Pubmed), Naltrexone (Wikipedia)