Background. Partial agonists of α4b2 nicotinic acetylcholine receptors are the most effective treatment strategy for tobacco smoking cessation. They are able to alleviate withdrawal symptoms and to reduce smoking satisfaction.
The aim of this study was to review the efficacy and safety of nicotinic receptor partial agonists varenicline and cytisine, for smoking cessation.
Methods. A search for randomized controlled trials was done using the terms (“cytisine”, “tabex”, “varenicline” or 'partial agonists of nicotinic receptors’) in MEDLINE, EMBASE, eLibrary in May 2018. Types of participants, the doses and duration of the treatments, efficacy and safety parameters, quality of randomization and blinding procedures were evaluated. Bayesian network meta-analysis was performed.
Results. Cytisine overcame placebo in the 12, 24 and 52 weeks of therapy with the following odds ratios (ORs) for abstinence: 3.3 (95% CrI 1.8–5.8), 3.9 (2.4–6.7), 3.8 (CrI 1.3–11,9) accordingly. Varenicline in 2 mg/day dose overcame placebo in the 12, 24 and 52 weeks of therapy with the ORs: 4.0 (3.3–4.7), 3.1 (2.5–3.7), 2.9 (2.2–4.1) accor dingly. Varenicline in 1 mg/day dose overcame placebo in 12 and 52 weeks of therapy, the ORs were 3.0 (2.0–4.7) and 2.3 (1.3–4.4) accordingly. Varenicline in 0.5 mg/day dose overcame placebo in 12 weeks of therapy only with the OR 2.4 (1.3–4.4). Cytisine and varenicline 2 mg/day were associated with more gastrointestinal disturbances than placebo with the ORs 6.2 (2.1–22.8) and 2.4 (2.0–2.8) accordingly. Cytisine and varenicline 2 mg/day were associated with more psychiatric problems than placebo with ORs 5.2 (1.9–15.1) and 1.6 (1.3–1.9) accordingly. There was no difference in serious adverse events between the investigated drugs and placebo: OR for cytisine was 2.4 (0.8–6.8), varenicline 0.5 mg/day – 2.0 (0.5–6.6), varenicline 1.0 mg/day – 1.0 (0.3–2.7), varenicline 2 mg/day – 1.0 (0.7–1.4).
Conclusion. Cytisine was proved to be as effective and safe aid for smoking cessation as varenicline.
Nicotine receptor partial agonists for smoking cessation
