Drug may help smokers quit, 3 studies find

CHICAGO — A new medication that reduces the craving for cigarettes and abates withdrawal symptoms appears to be more effective in helping people break the smoking habit than the best therapy currently available, the nicotine-replacement drug bupropion, according to three studies published Tuesday.

Although the new anti-smoking drug, varenicline, is seen as a step forward, experts cautioned that it is less effective than health officials would like and that there may never be a pill to help most smokers quit.

"Varenicline definitely is not a panacea for smoking cessation," Robert Klesges of the University of Tennessee Health Science Center wrote in an editorial accompanying the studies in the Journal of the American Medical Association.

"Many participants in these trials experienced adverse events, stopped taking their study medication before they should have, and discontinued participation in the studies. Importantly, the majority of participants in these three studies did not quit smoking even with varenicline."

Nevertheless, anti-smoking therapists, as well as smokers wanting to quit smoking, "now have another product available that appears to help increase the probability of smoking cessation," Klesges and his colleagues wrote.

The drug, approved by the FDA in May, will be marketed under the trade name Chantix and is expected to be available by August. The Centers for Disease Control and Prevention estimates that 44.5 million U.S. adults smoke and that 8.6 million of them have at least one serious illness, such as cancer or heart disease, caused by smoking.

Two of the studies in JAMA, involving a total of more than 2,000 smokers, found that 44 percent of people taking varenicline up to 12 weeks continued to abstain from smoking, compared with about 30 percent for bupropion, marketed as Zyban, and 17 percent for those taking an inert placebo. After 52 weeks, 22 to 23 percent of those on varenicline were still not smoking compared with 14 to 16 percent taking bupropion.

Only 8 to 10 percent of smokers on placebos were still abstinent after one year. The pharmaceutical giant Pfizer, which will manufacture varenicline, supported all of the studies.

Four out of 10 smokers attempt to quit each year, but only about 10 percent are successful. Nicotine-replacement compounds, such as bupropion and patches, are commonly used to help people quit, but their success rate is only moderate.