Business Times – 12 Apr 2008
By LIM WEN JUIN
SMOKERS here are finally getting a new aid to help them kick the habit, with the Singapore launch of Pfizer’s Champix. This is the first approved anti-smoking drug here in almost 10 years.
The other two existing anti-smoking treatments are nicotine replacement therapy (NRT) and the drug bupropion, which were approved by the Health Sciences Authority in 1991 and 1999 respectively.
Champix, a prescription drug, is a new class of treatment because it disrupts the mechanism by which nicotine brings about pleasure.
Nicotine, the substance in cigarette smoke that causes addiction, binds to alpha-4/beta-2 receptors in the brain, which triggers the pleasure-inducing release of the neurotransmitter dopamine.
Champix’s active ingredient, varenicline, binds to nicotine’s alpha-4/beta-2 receptors, reducing the withdrawal symptoms and nicotine craving brought about by cessation of smoking. Cessation of smoking leads to physical and psychological withdrawal symptoms – including headaches, tiredness, insomnia, irritability and depression – which result in a craving for nicotine.
At the same time, varenicline prevents nicotine from binding to the receptors – this means that a Champix user who smokes will experience little pleasure from the cigarette, helping to reduce dependency on smoking.
The Champix treatment is designed to last 12 weeks in order to help users overcome the worst withdrawal symptoms. Thereafter, the severity of the symptoms drops to a steady, more manageable plateau.
Ong Kian Chung, consultant respiratory physician at Mount Elizabeth Medical Centre, explains that withdrawal symptoms are most pronounced in the first three or four months after cessation of smoking.
Clinical trials involving more than 2,000 smokers over a 12-week period of therapy concluded that patients on Champix were two times more likely to quit smoking than bupropion users, and four times more likely to quit compared to those without pharmological assistance.
A 12-week course of Champix costs $660, which works out to about $8 a day. The chief side effect, reported by 33 per cent of users, is nausea, but discontinuation rates are lower than 3 per cent.
Dr Ong cautions, however, that there is still a danger of relapsing long after the most trying initial period has passed. In its end-2007 survey in Singapore of 200 respondents, independent agency Saffron Hill found that among unsuccessful quit attempts, smokers stopped smoking for an average of seven months before succumbing again.
A separate study was conducted on 1,210 smokers who quit after 12 weeks on Champix. For a further 40 weeks, one group was given Champix, while the other was given a placebo. Forty-four per cent of the former group abstained from smoking throughout this period, compared to 37 per cent of the latter.
Ultimately, Dr Ong advises that while Champix shows promise, smokers seeking to quit should also seek professional help. The Saffron Hill survey found that while 24 per cent of smokers approached friends or relatives for help to quit smoking, only 11 per cent approached their family doctors.
Even more dismally, a mere 3 per cent approached smoking cessation clinics or the Health Promotion Board, and just one per cent sought assistance from specialists.