Varenicline, the prescription smoking cessation drug marketed as Chantix®, hasn’t led to a significant decrease in the number of Americans who have successfully quit smoking, according to a study led by researchers at Moores Cancer Center at the University of California San Diego (UC San Diego).
Rather, varenicline’s main effect on the market has been to take the place of other existing pharmacotherapies, such as nicotine replacement therapy and bupropion (marketed as Zyban®), the researchers found. Their results were published online August 17, 2015 in Tobacco Control.
Smokers using varenicline were less likely to relapse in the first 3 months of quitting compared with smokers who used the other pharmacotherapies, the researchers found. But that initial advantage disappeared after 3 months, which coincides with the recommended length of use for varenicline. In other words, the difference between therapies became insignificant once smokers stopped using them.
“We had hoped the new pharmacotherapy would help more people quit, but this is not what is happening,” said lead author Shu-Hong Zhu, PhD, professor in the Department of Family Medicine and Public Health and director of Center for Research and Intervention in Tobacco Control at UC San Diego. “Instead, varenicline is replacing other options like the patch, without having any significant population-level impact on quitting success.”
Chantix generated considerable excitement when it was first approved by the FDA in 2006 for the treatment of nicotine dependence. Several studies have investigated the drug's impact in overall use of pharmacotherapy. But no study had looked into whether varenicline has reduced the population cessation rate.
So, this study used two U.S. Census Bureau surveys of adult smokers (ages 18 and older) conducted in 2003 and 2010 to 2011—before and after varenicline became available—and compared the smoking cessation rates between the two periods. Based on responses from more than 39,000 smokers, overall use of pharmacotherapy increased from 28.7% of smokers trying to quit in 2003 to 31.1% in 2010 to 2011—an increase of 2.4%. Although statistically significant, this slight increase in pharmacotherapy did not translate into more smokers breaking the habit—approximately 4.5% of smokers in 2003 reported successfully quitting for at least a year, compared with 4.7% in 2010 to 2011.
The authors wrote, “The new medication, varenicline, mainly attracted smokers who would normally use other therapies, instead of recruiting a new group of smokers who would otherwise not use any therapy. As such, even though the use of varenicline did increase dramatically (from 0% to 11% for all smokers and from 0% to 13% for daily smokers), the use of other therapies decreased significantly. The net result was a 2.4 percentage point increase in total therapy use among all smokers who made a quit attempt.”
Dr. Zhu said, “We are not saying Chantix does not help smokers quit. It does, but it won’t solve America’s tobacco epidemic unless it inspires more smokers to try to quit.”