Pfizer Inc.’s new smoking-cessation drug, Chantix, was better at helping people quit their habit in research studies than an older pill from GlaxoSmithKline.
In one study, 23 percent of smokers treated for 12 weeks with Chantix were still abstaining a year after treatment began, compared with 15 percent for those on Glaxo’s Zyban and 11 percent on a placebo, an inactive pill, researchers said in the July 5 Journal of the American Medical Association.
The drug isn’t a panacea. A majority of participants in three Pfizer-sponsored trials reported in the journal failed to stop smoking by using Chantix, and almost 30 percent reported nausea as a side effect, according to a commentary published with the studies.
“When a new drug comes out, it is the latest magic bullet and everybody expects to quit smoking,” said the commentary’s lead author Robert Klesges. “It’s almost always unrealistic.”
Pfizer provided funds for the studies, according to footnotes to the research. In addition, some of the researchers were employees of Pfizer or had received consulting fees or honoraria from the company, or had ties with other companies with an interest in smoking-cessation drugs, the scientists disclosed.
Smoking leads to about 438,000 deaths annually in the U.S., scientists say. While almost 41 percent of smokers try to quit in any given year, only about 10 percent succeed, according to research. Drug use might double the odds of quitting, and a combination of drugs and behavioral therapy might quadruple the chances, Klesges said.
Chantix, or varenicline, won U.S. regulatory clearance in May. The drug might generate $1.2 billion in annual sales by 2010, New York-based Pfizer, the world’s largest drug company, told analysts on Feb. 10.
Robin Gaitens, a spokeswoman for U.K.-based GlaxoSmithKline, didn’t return a phone call seeking comment on the journal reports.
Karen Reeves, a Pfizer scientist who participated in the studies, said in a statement that the findings suggest Chantix provides smokers “new hope.”
“While data show that Chantix is an effective treatment for smoking cessation, it is important that patients are highly motivated to quit, and that they take a comprehensive approach to quitting smoking,” including therapy to modify behavior, Reeves said.
Most anti-smoking agents, such as nicotine gum, supply an alternative source of nicotine, the substance in cigarettes to which people grow addicted. Zyban, which in May 1997 won approval by the Food and Drug Administration for U.S. sale, is an antidepressant that reduces the craving for nicotine.
Chantix works a different way and gives doctors another type of weapon against smoking, Klesges said.
In one study of more than 1,000 smokers, researchers led by Douglas Jorenby of the University of Wisconsin in Madison found that 44 percent of Chantix users refrained from smoking during the last third of a 12-week period of drug use, compared with 30 percent for Zyban and 18 percent for a placebo.
Klesges said he pays little heed to 12-week figures, as many people relapse into smoking. He said he gives more credence to the 52-week results. The Jorenby study found that 23 percent of Chantix users were still abstaining a year after treatment began, compared with 15 percent for Zyban, or bupropion.
In a second study of more than 1,000 patients, scientists led by David Gonzales of Oregon Health & Science University in Portland also found an edge at the 52-week mark for the new drug. That finding, unlike Jorenby’s, wasn’t statistically meaningful, according to Klesges.
In the study led by Jorenby, 29 percent of Chantix users reported nausea, compared with 7 percent for Zyban and 10 percent for the placebo, the researchers reported.
Other side effects of the new drug were increased constipation and flatulence, according to the report.