Smokers taking an experimental drug in late-stage clinical trials
were twice as likely to quit as those who took bupropion, the old standby for
smoking-cessation treatment, according to findings presented at an American
Heart Association meeting in Dallas in November.
These findings were also announced in a press release from Pfizer Inc. last
month. The company makes the new drug.
In two double-blind, placebo-controlled studies conducted in the United
States, about 2,000 smokers received the experimental drug, varenicline,
another group received bupropion (marketed under the brand name Zyban), and a
third group received placebo for a duration of 12 weeks.
Varenicline, which is manufactured by Pfizer, is a selective nicotinic
acetylcholine receptor partial agonist and is designed to bind to the same
receptor sites as nicotine.
In addition to relieving the craving and withdrawal symptoms associated
with quitting smoking, the drug blocks the rewarding effects of nicotine.
In both studies, 44 percent of those treated with varenicline quit smoking
by the end of the 12-week treatment period, while just 30 percent of those
taking bupropion did. Of those taking placebo, 18 percent quit.
According to the data, the odds of quitting smoking for subjects taking
varenicline were about two times higher than for those taking bupropion and
four times higher than for those on placebo.
After a year, patients who received varenicline were significantly more
likely to have abstained from smoking than were those who took bupropion. (The
odds ratio for varenicline vs. bupropion was about 1.5).
In a third trial conducted at study sites in the United States and Europe,
researchers randomized 1,206 subjects who had quit smoking after 12 weeks of
varenicline treatment to another 12 weeks of either placebo or continuing
treatment with varenicline.
Researchers followed the subjects for 28 weeks and found that 71 percent of
those who received the additional treatment with varenicline remained
abstinent after six months, compared with 50 percent who received placebo.
According to Pfizer's press release, varenicline was well tolerated in all
three trials, and the side effects cited most frequently were nausea,
headache, trouble sleeping, and abnormal dreams.
Pfizer submitted a new drug application for varenicline to the Food and
Drug Administration in November, and if it is approved the drug will be
marketed under the brand name Champix.
More information about varenicline is posted at<www.pfizer.com>.▪