MONDAY, Oct. 9, 2006 (HealthDay News) -- Women -- but not men -- hoping to kick the smoking habit may be helped in the short-term by taking an opiate blocker drug in conjunction with standard nicotine patch treatments and counseling, new research suggests.
The medication -- naltrexone -- has been around for about 30 years and is already approved by the U.S. Food and Drug Administration for the treatment of alcohol and heroin dependence.
Naltrexone also prevented the weight gain that commonly comes with quitting smoking. Those who did not get the drug gained about four pounds in the first month after quitting; those who took the drug gained only one pound, the study found.
The new findings suggest that a two-month regimen, incorporating naltrexone, nicotine patches and behavioral support, improves by nearly 50 percent a woman's ability to abstain from smoking for the duration of the program, compared to the same program minus naltrexone.
But, naltrexone doesn't appear to offer similar help for men, according to the study, which was published in the October issue of Nicotine and Tobacco Research.
"Women have historically not responded as well as men to smoking-cessation treatment, so treatment strategies that show promise with helping them are very interesting," said study author Andrea King, an associate professor of psychiatry at the University of Chicago.
The study authors noted that naltrexone is thought to reduce cigarette and alcohol craving by blocking drug-induced brain signals that convey pleasure.
King and her colleagues studied the potential benefits of the drug among 110 men and women who smoked between 15 and 40 cigarettes a day for an average of 25 years. The study participants ranged in age from 21 to 65, and all were healthy and motivated to stop smoking.
As part of the two-month program, all the participants attended six counseling sessions with a therapist, and all used daily nicotine patches of decreasing intensity over the course of the first four weeks.
Half the participants also took 50 milligrams daily of naltrexone for eight weeks, while the other half took a placebo.
Weekly assessments were conducted, as was a post-program check-up six months after the initial quit date.
King and her colleagues evaluated cigarette use, cravings, and treatment side effects. They found that at the end of the two-month period, men had better overall success at quitting than women did -- a typical result observed in most standard cessation therapies.
But, they noted that most of the difference was confined to the non-naltrexone group.
Among those taking naltrexone, both men and women had similar two-month cessation success rates: 62 percent among the men and 58 percent among the women. Men not taking naltrexone had nearly the same cessation success rate as their naltrexone counterparts. However, the women not taking the opiate blocker had only a 39 percent success rate.
The researchers noted that naltrexone appeared to help women reduce their cravings for cigarettes as well as the typical discomforts associated with tobacco withdrawal.
Yet, while the drug didn't appear to influence the men's quit rate, King and her team did find that naltrexone reduced both male and female weight gain commonly experienced by quitters.
Those on the medication gained only one pound in the first month after quitting, while the non-drug group gained approximately four pounds.
Most naltrexone side effects, such as nausea and light-headedness, were mild, and only light-headedness persisted beyond the first month.
On the minus side, the researchers noted that at six months after treatment, the overall success rates ultimately dropped to around one-third of all study participants. It could be that a longer initial regimen including naltrexone would offer better and longer-lasting results, the scientists said.
"This is a treatment option that needs more study, but I am optimistic," said King. "And, in the end, it may be that this kind of aggressive treatment somehow addresses both psychological and biological issues that are at play which could account for the complexities of smoking as they specifically relate to women."
King said she's now conducting a study that's three times larger than the first one. She hopes it will help unravel the mechanisms that underlie the drug's affect.
Dr. Joseph R. Di Franza is a professor of family medicine and community health at the University of Massachusetts School of Medicine who has studied smoking cessation. He said he was surprised because he's never heard of a quit-smoking strategy that worked better for one sex than the other.
"I would say that this type of medication works by blunting the cravings that are induced by cues in the environment even after the withdrawal has gone away -- like seeing someone else smoke or smelling a cigarette," Di Franza said. "And there is some non-definitive research that indicates that for women, smoking is driven more by those kinds of cues. So, if men are immune to those cues, that might explain why this drug has no added benefit for them. But we certainly would want to see these findings replicated in future studies."
For more information on quitting smoking, visit smokefreee.gov.