Varenicline Prevents Relapse of Smoking Behaviour
Jul 5, 2006 - 7:11:37 PM

In a study, Serena Tonstad, M.D., Ph.D., of Ulleval University Hospital, Oslo, Norway and colleagues with the Varenicline Phase 3 Study Group conducted a randomized, double-blind, placebo-controlled trial evaluating the efficacy of an additional 12 weeks of varenicline used for relapse prevention in smokers who successfully achieved abstinence following an initial 12-week varenicline treatment.

According to background information in the article, 50 percent to 60 percent of people who are initially successful at quitting smoking go on to relapse within a year. A recent comprehensive review of existing studies concluded that currently there is no evidence-based relapse prevention intervention available.

The study was conducted at multiple medical clinics in 7 countries with follow-up to 52 weeks after study baseline. Of 1,927 cigarette smokers recruited between April 2003 and February 2004 and treated for 12 weeks with open-label varenicline twice per day, 1,236 (64.1 percent) did not smoke, use tobacco, or use nicotine replacement therapy during the last week of treatment and 62.8 percent (n = 1,210) were randomized to additional treatment or placebo. Participants were assigned to receive either varenicline, 1.0 mg twice per day (n = 603), or placebo (n = 607) for an additional 12 weeks.

The continuous abstinence rate for weeks 13 to 24 was higher for participants randomized to varenicline than for participants randomized to placebo (70.5 percent vs. 49.6 percent). The continuous abstinence rate for weeks 13 to 52 was also higher for the varenicline group than for the placebo group (43.6 percent vs. 36.9 percent). Adverse events reported in the open-label period were mostly mild; no difference in adverse events between varenicline and placebo was observed during the double-blind period.

“In the field of relapse prevention—in which there is a notable lack of positive findings—these results represent an important new development,” the authors write.

The researchers add that at the end of this trial, as in all existing literature on smoking cessation with 1 year of follow-up, more than 50 percent of participants in each group returned to smoking. “Thus, an examination of longer medication periods is warranted.”

“In conclusion, 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,” the authors write.

In an accompanying editorial, Robert C. Klesges, Ph.D., Karen C. Johnson, M.D., M.P.H., and Grant Somes, Ph.D., of the University of Tennessee Health Science Center, Memphis, Tenn., comment on the studies on varenicline and smoking cessation.

“It is important for clinicians to moderate some of the potential enthusiasm that is likely to occur as the result of the publication of these trials, FDA approval of the drug, and promotion by this manufacturer. On the one hand, these studies demonstrate that varenicline is associated with higher smoking cessation rates than placebo and may produce better cessation rates than bupropion, a first-line–approved smoking cessation drug. Importantly, varenicline represents a third class of drug with probably a different mechanism of action than either nicotine replacement therapy or bupropion. On the other hand, varenicline definitely is not a panacea for smoking cessation. 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 3 studies did not quit smoking even with varenicline.”

“Clearly, quitting smoking, even with pharmacological and behavioral assistance, is extremely difficult. Patients currently cannot and probably never will simply be able to ‘take a pill’ that will make them stop smoking. Smokers must want to stop smoking and must be willing to work hard to achieve the goal of smoking abstinence,” the authors write. “Although much research needs to be conducted to establish the effectiveness of varenicline, stop smoking researchers and clinicians, as well as smokers wanting to quit smoking, now have another product available that appears to help increase the probability of smoking cessation.”

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