A recently licensed nicotine receptor stimulant trebles the odds of stopping smoking

The new anti-smoking drug varenicline was first licensed for use in the UK on 5th December 2006. An early Cochrane Review' of its effectiveness shows that it can give a three-fold increase in the odds of a person quitting smoking. Varenicline is the first new anti-smoking drug in the last ten years, and only the third, after NRT and bupropion, to be licensed in the USA for smoking cessation.

People become addicted to smoking tobacco partly because nicotine in the smoke stimulates receptors in the nervous system that cause a release of the feel-good hormone dopamine. Varenicline partially stimulates these nicotine receptors and enables a low-level release of dopamine, which reduces withdrawal symptoms. It also partially blocks nicotine from being absorbed by the receptors, making continued smoking less satisfying. This reduces a person’s need to smoke, and may help them to quit completely.

This conclusion was drawn by a group of Cochrane researchers after they studied data from six trials that compared the effects of giving people either varenicline or a placebo. Together the trials involved 2451 people on varenicline and 2473 people on placebos.

Pooling the data showed that people taking varenicline increased their odds of quitting approximately three-fold for 12 months or longer compared with those on placebo drugs .

Data from some of the trials also showed that people given varenicline increased their odds of quitting more than 1½-fold compared with those given bupropion, an antidepressant drug that roughly doubles a person’s chance of stopping smoking (see: next press release.)

“What we need now are some trials that make direct comparisons between varenicline and nicotine replacement therapy” says Lead Review Author Kate Cahill, who works in the Department of Primary Health Care at Oxford University.