LONDON (Reuters Health) - For women, the effectiveness of nicotine patches for smoking cessation depends on their genotype for the dopamine D2 receptor gene DRD2 32806, British researchers report.
Dr. Patricia Rudkin and colleagues from the University of Oxford took blood samples from 752 people who had taken part in a randomized controlled trial of nicotine patches roughly 8 years earlier, to test for variants of the gene.
The variant T allele of the receptor gene was found in 41% of women and 41% of men. The researchers then correlated genotype with effectiveness of the patients - measured by the relative odds of abstinence at one week, 12 weeks, 24 weeks, 52 weeks and to follow-up.
“In women, the effectiveness of the patches differed with genotype at all time points,” the authors write in the British Medical Journal Online First available March 19. “In men the genotype did not differ significantly at any time.”
For example, at 52 weeks, 15% of women with the T allele (CT or TT genotypes) were abstinent from smoking, compared to 8% of those with the CC genotype. In men, the rates were 13% and 16% respectively.
“The nicotine patch increases the chance of giving up by about 3 times for women with the CT/TT genotype [relative to placebo], while it doesn’t increase the chance at all for women with the CC genotype,” Dr. Rudkin told Reuters Health. “On the other hand, women with the CC genotype seem to find to easier to give up without the patch than do those with the CT/TT genotype.”
If nicotine replacement was targeted at those most likely to respond, its overall effectiveness might be improved, Dr. Yudkin’s team writes. Their results suggest that the therapy works through different processes, and is influenced by different genetic mechanisms in men and women.
“We’re not ruling out a genetic impact on patch efficacy in men,” she added in an email interview. “Only that it might be through some other mechanism.”
BMJ Online First www.bmj.com
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