Three months following its approval by the US Food and Drug Administration, Pfizer yesterday said its smoking cessation therapy Chantix (varenicline) is now available in pharmacies at a reported cost of just over $3 a day for a 12-week course. Chantix is the first non-nicotine product to be given the thumbs up by US drug regulators since the approval of GlaxoSmithKline’s antidepressant Wellbutrin – under the brand name Zyban - for the same indication.

In clinical trials, about 44% of patients taking Chantix had stopped smoking at the end of the 12-week trial period, compared to about 30% of those taking Zyban and about 18% receiving placebo. At the end this period, patients who quit on Chantix were offered a further 12 weeks’ therapy and, at the culmination of this study period, 71% of patients who continued on Chantix remained smoke-free compared to 50% who switched to placebo.

There are 45 million adult smokers in the US, but approximately 70% say they want to quit, says Pfizer. According to the American Lung Association, the economic cost of smoking on an annual basis is approximately $167 billion, making the issue of vast importance to the country’s health. And, aside from its efficacy, those individuals prescribed Chantix will also be able to take up a free, one-year behavioural modification and support programme called Getquit, developed by Pfizer, which can be accessed by phone or over the internet.

Chantix has a dual approach to helping smokers quit; it blocks the pleasure receptors in the brain associated with cigarette smoking and nicotine, and cuts the level of withdrawal symptoms that often drive a return to the addiction. If a person does smoke while taking Chantix, the drug may block nicotine from binding and lessen its effects. The most frequently reported adverse events were nausea, headache, insomnia and abnormal dreams.

Pfizer, which has seen its share price suffer of late, will have been pleased to see it take an upturn yesterday – albeit closing at the same level as the previous day’s price of $25.99. The firm’s stock has almost halved during the tenure of the incumbent chief executive, Hank McKinnell, who this week it was announced would be leaving as chief executive ahead of his expected departure date in 2008. He has been criticised for drawing a hefty remuneration package at a time when Pfizer has to restructure to maintain its competitiveness.