Gene May Affect Success With Nicotine Patch

For many women, the products may not be an effective solution

THURSDAY, March 18, 2004 (HealthDayNews) -- The nicotine patch is considered the first choice in helping people quit smoking, but now a new British study brings that into question for many women.

The research indicates women who have a certain gene variation may not benefit from using the nicotine patch, while other women and men do.

"It was a very big surprise to find that this particular genetic variation works differently in men and women, because normally you wouldn't expect genes to work differently in men and women," says lead researcher Patricia Yudkin, an instructor in the Department of Primary Health Care at the University of Oxford in England.

This gene is located on the dopamine receptor called DRD2 32806 C/T. Dopamine is a chemical manufactured in the brain that transmits messages between brain cells, and is associated with pleasure, emotions and addiction. It also speeds up the release of nicotine, Yudkin says.

For women with the most common variation of this dopamine receptor, nicotine patches are not very effective, researchers report.

"This is a very early finding," Yudkin says. "This doesn't mean that it is absolutely true -- it may turn out not to be true," she adds.

And one expert on smoking cessation notes the finding has no immediate practical application because most women would be unable to learn if they possess the gene variation.

Yudkin's team looked at an earlier study that focused on the effectiveness of the nicotine patch among 752 heavy smokers. Some of the individuals received real nicotine patches, while others received dummy patches.

The subjects wore their patches for 12 weeks, and then were followed for eight years, according to the report in the March 19 issue of the British Medical Journal.

There are three gene variations labeled CT, TT, and CC. It is the CC variation, the most common, which appears to prevent the patch from being effective in women. However, the effectiveness of the patch in men with the CC variation is not affected.

After 12 weeks of wearing the patch, 23 percent of women with the so-called CT or TT gene variation had stopped smoking, compared with only 13 percent of the women with the CC variation. For men, 25 percent with the CT or TT variation had quit, as had 23 percent with the CC variation, the researchers found.

After eight years, 12 percent of the women with the CT or TT variation remained smoke-free, compared with 5 percent of the women with the CC variation. For men after eight years, 10 percent with the CT or TT variation were smoke-free, as were 13 percent with the CC variation.

Yudkin says she's not sure why this genetic variation has this effect. It may have to do with the number of dopamine receptors on the various gene variations, she speculates.

"Many genes are involved in smoking behavior, including why people smoke, how much they smoke and how difficult it is to give it up," Yudkin says. "So there might be a difference between the genes involved in smoking for men and women."

Yudkin suspects the new finding would hold true for other methods of nicotine replacement, such as nicotine gum and nasal spray.

If this finding holds up, then one might be able to target therapy to individual women, Yudkin says. For example, women with the CC variation would get other therapies, she says.

Jed E. Rose, director of the Nicotine Research Program at Duke University Medical Center and co-inventor of the nicotine patch, says "these findings represent a potentially exciting approach of ultimately being able to tailor therapy for different subtypes of smokers."

However, finding out which gene variation one has is not easily available to most smokers, Rose says.

"So an individual woman smoker has no way of knowing if she falls into the subclass for which the patch showed efficacy. Thus, there is no immediate application of the genetic associations for those wanting to quit smoking," he adds.

Rose notes the long-term success rates were low even among those for whom the patch worked. "Smokers should be encouraged to use more than one behavioral or pharmacologic aid to quit smoking in order to maximize their chances for success," he says.

More information

The American Lung Association can tell you about nicotine-replacement therapy. The National Cancer Institute has information on how to quit smoking.

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