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Clinical Trial Results

Summaries of Newsworthy Clinical Trial Results
  • Posted: 11/03/2011

Smoking Cessation Drug Proves Effective in Single-Center Trial

Adapted from the NCI Cancer Bulletin.

In a single-center randomized controlled trial, the smoking cessation drug cytisine was more effective than a placebo at helping participants abstain from smoking. Results from the trial, conducted at the Maria Sklodowska-Curie Memorial Cancer Center in Warsaw, Poland, appeared in the September 29, 2011, issue of the New England Journal of Medicine.

Cytisine binds to the alpha-4 beta-2 nicotinic acetylcholine receptor, which has been implicated in nicotine dependence and is the primary target for the smoking cessation drug varenicline. Cytisine has been available for more than 40 years as a smoking cessation aid in some eastern European countries, although results from animal studies have suggested that cytisine might have limited efficacy in humans.

The research team randomly assigned 740 participants to receive cytisine or a placebo for 25 days. All study participants received a minimal amount of counseling. Twelve months after the end of treatment, 31 participants in the cytisine group and 9 in the placebo group remained smoke-free, an abstinence rate of 8.4 percent versus 2.4 percent. Smoking abstinence was verified by measuring the carbon monoxide concentration in exhaled breath.

Cytisine resulted in more gastrointestinal adverse events than did placebo, but rates of other adverse events and death were similar in the two groups. The rates of discontinuation or dose reduction were also similar with cytisine and placebo.

“Combining cytisine with more intensive behavioral support may result in higher absolute quit rates,” wrote the authors, “and it is possible that efficacy could be improved by a longer regimen.” They also noted that the lower cost of cytisine as compared with that of other smoking-cessation drugs “may make it an attractive treatment option for smokers in low-income and middle-income countries.”

Michele Bloch, M.D., Ph.D., acting branch chief of NCI’s Tobacco Control Research Branch, noted, “The combination of cytisine with behavioral strategies is promising and worthy of further investigation.”

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