Placebo-Controlled Trial of Cytisine for Smoking Cessation
What is the efficacy and safety of cytisine, a partial agonist that binds with high affinity to the α4β2 nicotinic acetylcholine receptor, that is a low-cost treatment adjunct for smoking cessation used in European countries?
A single-center, randomized, double-blind, placebo-controlled trial was conducted in a smoking cessation center in Poland. Participants were randomly assigned to receive cytisine or matching placebo for 25 days; participants in both groups received a minimal amount of counseling during the study. The primary outcome measure was sustained, biochemically (carbon monoxide level) verified smoking abstinence for 12 months after the end of treatment. Of 1,542 adult smokers screened, 740 were enrolled and 370 were randomly assigned to each study group.
About 50% were male, average age was 48 years, 50% were working in manual labor, and 80% had tried to stop smoking previously. Average cigarettes smoked were 23 [standard deviation = 9], and mean Beck Depression score was 10.6 [7.6]. The rate of sustained 12-month abstinence was 8.4% (31 participants) in the cytosine group, as compared with 2.4% (nine participants) in the placebo group (difference, 6.0 percentage points; 95% confidence interval [CI], 2.7-9.2; p = 0.001). There was no relationship between abstinence and clinical variables. The 7-day point prevalence for abstinence at the 12-month follow-up was 13.2% in the cytosine group versus 7.3% in the placebo group (p = 0.01). Gastrointestinal adverse events were reported more frequently in the cytisine group (difference, 5.7 percentage points; 95% CI, 1.2-10.2).
The authors concluded that cytisine was more effective than placebo for smoking cessation. Additionally, the lower price of cytisine compared with that of other pharmacotherapies for smoking cessation may make it an affordable treatment to advance smoking cessation globally.
The 1-year rate of quitting is less than varenicline, but similar to nicotine replacement therapy. The effect of longer-term cytisine on the major concerns of neuropsychiatric symptoms and blood pressure has not been studied systematically.
Keywords: Depression, Outcome Assessment (Health Care), Nicotine, Follow-Up Studies, Receptors, Nicotinic, Poland, Vascular Diseases, Blood Pressure, Europe, Quinoxalines, Benzazepines, Cytosine, Azocines, Quinolizines, Carbon Monoxide, Tobacco Use Disorder, Smoking Cessation
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