Anti-smoking drug backed by 3 studies

Three studies released yesterday indicate that the newly approved drug varenicline is more effective than bupropion or a placebo in helping smokers overcome nicotine addiction.

“Varenicline was significantly more efficacious than placebo for smoking cessation at all time points and significantly more efficacious than bupropion SR at the end of 12 weeks of drug treatment and at 24 weeks,” David Gonzales of the Smoking Cessation Center of the Oregon Health & Science University wrote in one of the peer-reviewed reports, published in this week’s Journal of the American Medical Association (JAMA).

Although some anti-smoking specialists worry the publication of these positive findings will wrongly convince some smokers that Pfizer Inc.’s varenicline is a panacea, even the skeptics call it “promising.”

Most smoking-cessation drugs are nicotine-replacement therapies. But Pfizer’s varenicline, which is marketed as Chantix and was approved by the Food and Drug Administration (FDA) in May, is a non-nicotine drug that is thought to be beneficial for curbing smoking by stimulating the release of dopamine in the brain to reduce craving and withdrawal.

In the experiment, it was compared with GlaxoSmithKline’s sustained-release (SR) bupropion, an anti-smoking treatment without nicotine marketed as Zyban that has been on the market for nearly a decade.

When the FDA approved bupropion in 1997 as an anti-smoking aid, it was an antidepressant being sold as Wellbutrin. When the drug was approved for smoking cessation, its name became Zyban.

In the Oregon-led study, participants were randomly assigned to receive twice daily either varenicline, bupropion or a placebo for 12 weeks. They also underwent 40 weeks of nondrug follow-up.

The researchers found that continuous abstinence rate for weeks nine through 12 was 44 percent for those on varenicline, 29.5 percent for those on bupropion and 17.7 percent for those on placebo.

The abstinence rate for weeks nine to 24 was 29.5 percent for those on varenicline, 20.7 percent for those on bupropion and 10.5 percent for those on placebo.

For weeks nine through 52, the continuous abstinence rate was 2 times greater for those on varenicline than on placebo.

Mr. Gonzales and colleagues also said varenicline effectively reduced nicotine cravings and withdrawal. And those who smoked while receiving the drug said it reduced their smoking satisfaction.

A second large study by the University of Wisconsin School of Medicine and Public Health found similar results.

“At the end of the treatment period, the odds of quitting smoking with varenicline were significantly greater than the odds of quitting with either placebo or bupropion SR,” the authors said.

A third study in JAMA by Norwegian researchers evaluated the benefit of an additional 12 weeks of varenicline treatment compared with a placebo in relapse prevention among smokers who achieved abstinence after an initial 12 weeks of varenicline therapy.

“Extended use of varenicline helps recent ex-smokers to maintain their abstinence and prevent relapse. Varenicline is the first smoking-cessation treatment to demonstrate a significant long-term relapse prevention effect,” investigators at Ulleval University Hospital in Oslo concluded.

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