September 2, 2015
Varenicline Not Having Much Effect on Rates of Successful Tobacco Cessation

San Diego—Despite hopes to the contrary, the introduction of varenicline in 2006 hasn’t had much effect on the rate at which American adults successfully quit smoking, according to a new study.

A report published online recently by the journal Tobacco Control suggests instead, that the primary effect of varenicline, marketed as Chantix, has been to displace the use of older tobacco addiction therapies, such as nicotine replacement therapy (NRT) and the antidepressant bupropion, marketed as Zyban.

In the population analysis, researchers from the University of California, San Diego School of Medicine also report that varenicline’s enhanced effectiveness in helping smokers quit lasted for only 3 months, at which point varenicline users no longer had higher rates of success than those using other tobacco-cessation methods.

“We had hoped the new pharmacotherapy would help more people quit, but this is not what is happening,” lead author Shu-Hong Zhu, PhD, said in a UC San Diego press release. “Instead, varenicline is replacing other options like the patch, without having any significant population-level impact on quitting success.”

Varenicline binds to nicotine receptors in the brain, reducing cravings by stimulating the release of dopamine, a neurotransmitter that helps regulate the brain’s reward and pleasure centers. The study found that varenicline use increased from 0% in 2003 to 10.9% in 2010-2011, while use of bupropion decreased from 9.1% to 3.5%, and NRT from 24.5% to 22.4%.

For the study, researchers analyzed two U.S. Census Bureau surveys of smokers age 18 and older that had been conducted before—in 2003—and after, 2010-2011, varenicline became commercially available. Those surveys looked at the following:

• Smokers’ efforts to quit in the last 12 months;
• Use of nicotine-replacement therapies, including the nicotine patch, gum, lozenge and inhaler; and
• Effectiveness of prescription medications such as bupropion and varenicline.

Responses from more than 39,000 smokers indicated that overall use of pharmacotherapy jumped up from 28.7% of smokers trying to quit in 2003 to 31.1% in 2010-2011, a 2.4% increase.

That did not lead to a significant increase in smokers able to break the habit, however: In 2003, about 4.5% reported successfully quitting for at least a year, compared to 4.7% in 2010-2011, according to the report.

“Addition of varenicline to the list of approved cessation aids has mainly led to displacement of other therapies,” study authors conclude. “As a result, there was no meaningful change in population cessation rate despite a remarkable increase in varenicline use. The population impact of a new therapy is a function of more than efficacy or reach of the therapy.”

“We are not saying Chantix does not help smokers quit,” Zhu added. “It does, but it won't solve America's tobacco epidemic unless it inspires more smokers to try to quit.”
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