File photo of cigarettes are seen during manufacturing process in BAT Cigarette Factory in Bayreuth
Lucky Strike cigarettes are seen during the manufacturing process in the British American Tobacco Cigarette Factory (BAT) in Bayreuth, southern Germany, April 30, 2014. Reuters/Michaela Rehle/File Photo

The speed at which smokers metabolise nicotine in their bodies may determine how they can quit, new research shows.

Nearly 70 per cent of smokers relapse into smoking within a week of trying to quit. The new findings may help them stop smoking for good. The study, published in The Lancet Respiratory Medicine journal, is the largest pharmacogenetic study of tobacco dependence so far. It concludes that slow metabolisers of nicotine have a better chance of responding to the nicotine patch, compared to faster metabolisers who have better chances of quitting smoking when they use non nicotine replacement drug varenicline, sold as Chantix or Champix.

Slow and normal metabolisers of nicotine differ in how long nicotine stays in their body. Nicotine levels drop more quickly in normal metabolisers, and they are therefore at greater risk of having cravings and relapsing into smoking once they quit.

The study, led by the University of Pennsylvania in the United States, says that about 60 per cent of smokers are normal metabolisers and nicotine levels in these people's bodies drop more quickly. A total of 1,246 smokers who wanted to quit were assigned to 11 weeks of either the nictone patch and a placebo pill, varenicline and a placebo patch, or a placebo pill and patch; 662 of these people were slow metabolisers and 584 were normal metabolisers of nicotine. These people were given behaviourial counselling and were followed for 12 months after their quitting date.

At the end of the 11-week period, normal metabolisers were about twice as likely to quit smoking if they were taking verenicline, compared to those normal metabolisers who were taking the nicotine patch. They were significantly more likely to abstain from smoking six months later as well. Though verinicline was equally effective for slower metabolisers of nicotine, they reported greater side effects from the drug.

More than six million people die of smoking-related diseases every year, and about $200 billion is spent on tobacco-related healthcare worldwide. Previous treatments into the relationship between smoking cessation treatments and metabolism have not been tested, and so far, the drug varenicline has not been included in any research on the topic.

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