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.
Effects of varenicline on smoking cessation in patients with mild to moderate COPD: a randomized controlled trial.
Smoking is the most important risk factor for COPD and accelerates its progression. Despite the health implications, a large proportion of patients with COPD continue to smoke, so finding effective smoking cessation interventions for this population is paramount. To our knowledge, this is the first randomized clinical trial to compare the efficacy and safety of varenicline tartrate vs placebo in smokers with mild to moderate COPD.
                In a 27-center, double-blind, multinational study, 504 patients with mild to moderate COPD (postbronchodilator FEV1/FVC, <70%; FEV1 percent predicted normal value, ≥50%) and without known psychiatric disturbances were randomized to receive varenicline (n=250) or placebo (n=254) for 12 weeks, with a 40-week nontreatment follow-up. The primary end point was carbon monoxide-confirmed continuous abstinence rate (CAR) for weeks 9 to 12. A secondary end point was CAR for weeks 9 to 52.
                CAR for weeks 9 to 12 was significantly higher for patients in the varenicline group (42.3%) than for those in the placebo group (8.8%) (OR, 8.40; 95% CI, 4.99-14.14; P<.0001). CAR in the patients treated with varenicline remained significantly higher than in those treated with placebo through weeks 9 to 52 (18.6% vs 5.6%) (OR, 4.04; 95% CI, 2.13-7.67; P<.0001). Nausea, abnormal dreams, upper-respiratory tract infection, and insomnia were the most commonly reported adverse events (AEs) for patients in the varenicline group. Serious AEs were infrequent in both treatment groups. Two patients in the varenicline group and one patient in the placebo group died during the study. Reports of psychiatric AEs were similar for both treatment groups.
                Varenicline was more efficacious than placebo for smoking cessation in patients with mild to moderate COPD and demonstrated a safety profile consistent with that observed in previous trials. Trial registry: ClinicalTrials.gov; No.: NCT00285012; URL: www.clinicaltrials.gov.