Efficacy and safety of cytisine versus nortriptyline for smoking cessation: A multicentre, randomized, double-blinded and placebo-controlled trial.

Background and objective: Cytisine serves as an affordable smoking cessation aid with acceptable safety profile. However, data comparing its efficacy and safety to standard therapies are limited. We aimed to examine efficacy and safety of cytisine compared to nortriptyline, which is the only approved smoking-cessation medication in Thailand.

Methods: A 12-month, multicentre, randomized, double-blinded, placebo-controlled trial was conducted. Participants aged ≥20 years who smoked ≥10 cigarettes/day were randomly assigned to receive a 25-day cytisine or a 12-week nortriptyline treatment course. Brief interventions (BI) for smoking cessation were provided to all participants. The primary outcome was biochemically verified continuous abstinence rate (CAR) at 12 months. Additionally, self-reported abstinence, verified by exhaled carbon monoxide (CO) ≤ 10 ppm, was collected at 2 weeks, 1, 3, 6 and 12 months to assess both CAR and 7-day point prevalence abstinence rate (PAR).

Results: A total of 1086 participants were recruited and randomized into cytisine (n = 540) and nortriptyline (n = 546) groups. The 12-month CAR was 12.22% for cytisine and 9.52% for nortriptyline. The relative difference was 0.03 (95% confidence interval [CI]; -0.01 to 0.06) and the relative risk was 1.28 (95% CI; 0.91-1.81). No differences were observed in secondary outcomes between both groups. The incidence of adverse effects from cytisine appeared to be lower than that of nortriptyline.

Conclusion: At 12 months, cytisine plus BI was as effective as nortriptyline plus BI for smoking cessation. The adverse events for both cytisine and nortriptyline were minimal and well-tolerated.