Cytisine increases the chances of quitting, although absolute quit rates were modest in two recent trials. Varenicline at standard dose increased the chances of successful long-term smoking cessation between two- and threefold compared with pharmacologically unassisted quit attempts. Lower dose regimens also conferred benefits for cessation, while reducing the incidence of adverse events. More participants quit successfully with varenicline than with bupropion. Two open-label trials of varenicline versus NRT suggested a modest benefit of varenicline but confidence intervals did not rule out equivalence. Limited evidence suggests that varenicline may have a role to play in relapse prevention. The main adverse effect of varenicline is nausea, but mostly at mild to moderate levels and tending to subside over time. Possible links with serious adverse events, including serious psychiatric or cardiovascular events, cannot be ruled out.

Future trials of cytisine may test extended regimens and more intensive behavioural support. There is a need for further trials of the efficacy of varenicline treatment extended beyond 12 weeks.
Placebo-controlled trial of cytisine for smoking cessation.
Cytisine, a partial agonist that binds with high affinity to the α(4)β(2) nicotinic acetylcholine receptor, is a low-cost treatment that may be effective in aiding smoking cessation. This study assessed the efficacy and safety of cytisine as compared with placebo.
                We conducted a single-center, randomized, double-blind, placebo-controlled trial. 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 verified smoking abstinence for 12 months after the end of treatment. Of 1542 adult smokers screened, 740 were enrolled and 370 were randomly assigned to each study group.
                The rate of sustained 12-month abstinence was 8.4% (31 participants) in the cytisine group as compared with 2.4% (9 participants) in the placebo group (difference, 6.0 percentage points; 95% confidence interval [CI], 2.7 to 9.2; P=0.001). The 7-day point prevalence for abstinence at the 12-month follow-up was 13.2% in the cytisine 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 to 10.2).
                In this single-center study, cytisine was more effective than placebo for smoking cessation. The lower price of cytisine as compared with that of other pharmacotherapies for smoking cessation may make it an affordable treatment to advance smoking cessation globally.