Health Canada has given the nod to the first smoking-cessation drug to hit the market in a decade. 

Champix — which was discovered and developed by Pfizer — is one of two quit-smoking drugs that are not designed to replace the nicotine kick that cigarettes offer.

The drug works in two ways — by cutting the pleasure of smoking and reducing the withdrawal symptoms that frequently derail smokers' efforts to quit. If a person smokes while taking Champix, the drug can reduce the sense of satisfaction associated with smoking.

Champix latches on to the same receptors in the brain that nicotine binds to when inhaled in cigarette smoke. The action leads to the release of dopamine in the pleasure centres of the brain. Taking the drug blocks any inhaled nicotine from reinforcing that effect.

Most other stop-smoking drugs are nicotine-replacement therapies, either sold by prescription or over the counter in gum, patch, lozenge, nasal spray or inhaler form. The only other prescription drug sold to help people to quit smoking is Zyban. In the United States, Champix sold under the brand name Chantix.

Champix was approved for sale in Europe in 2006.

Several studies conducted in Europe on about 2,000 smokers showed that a year after initial treatment with Champix, a little more than one in five people stayed off cigarettes. Zyban's success rate is estimated at about 16 per cent. Only eight per cent of those who were given a placebo in the study had stopped smoking after a year.

Champix treatment includes 12 weeks of taking the drug as well as smoking-cessation counselling. Pfizer said the drug's possible side-effects include nausea, abnormal dreams, constipation, flatulence and vomiting.

According to Health Canada, more than 4.5 million Canadians — or about 18 per cent of the population age 15 years and older — smoke. More than 37,000 people die prematurely each year in Canada due to tobacco use and at least 800 non-smokers die every year from exposure to second-hand smoke.