Efficacy of cytisine in helping smokers quit: systematic review and meta-analysis

Abstract

Background A recent rigorous study has shown that cytisine, a low-cost drug, is effective for smoking cessation. A number of earlier studies exist, mostly from former communist countries where cytisine has been used since the 1960s. The key question now is whether there is sufficient evidence to warrant licensing cytisine or whether more work is needed. A systematic review was undertaken to assess the efficacy of cytisine in smoking cessation. Methods The Cochrane Library, CINAHL, Embase, Medline and PsycINFO databases were searched for relevant data. Data from controlled trials were entered into two separate meta-analyses. The first considered the strictest definition of outcome and longest follow-up from all available studies and the second pooled outcomes from studies with biochemically validated abstinence and follow-up of 6 months or longer. Results Eight controlled trials were identified. Seven trials provided extractable data and, when pooled (first meta-analysis), produced a risk ratio (RR) of 1.57 (95% CI 1.42 to 1.74). Data from two high-quality studies (second meta-analysis) produced a pooled RR of 3.29 (95% CI 1.84 to 5.90). Patients on cytisine reported more gastrointestinal symptoms than patients on placebo (RR=1.76, 95% CI 1.28 to 2.42). There was no difference in overall reports of adverse events and no specific safety concerns emerged. Conclusions Cytisine is an effective treatment for smoking cessation with efficacy comparable to that of other currently licensed treatments. Given its low cost and potential for public health benefit, expedited licensing of cytisine for smoking cessation is warranted. BACKGROUND

Nicotine vaccination—does it have a future?

“…Moreover, we also have the very low-cost drug, cytisine, as an option [18]. This raises a serious question as to whether substantial further investment in nicotine vaccines will be worthwhile from either commercial or public health perspectives.…”

What is the clinical effectiveness and cost-effectiveness of cytisine compared with varenicline for smoking cessation? A systematic review and economic evaluation

“…Despite this, only two trials of good quality with a minimum of 6 months' follow-up that have evaluated the clinical efficacy of cytisine compared with placebo met the inclusion criteria for both the Cahill review 15 and the current review. The Hajek review 26 of cytisine identified more trials; however, these did not fit the inclusion criteria for the Cahill review 15 or this current review. The most common reason for this was that the length of follow-up was too short.…”

“…A recent review of the efficacy and safety of cytisine found it to be an effective treatment for smoking cessation. 26 The review highlights the low cost of cytisine and suggests that licensing of this drug may therefore be warranted because of its potential public health benefit. No head-to-head trials between varenicline and cytisine were identified in either review and, to date, no indirect comparisons of the two drugs have been conducted in the absence of such trials.…”

“…124 A review by Hajek et al 26 found that many of the cytisine trials provided minimal support to participants, for example the drug was distributed by post. They highlight that more intensive support during attempted smoking cessation increases quit rates, and that this may be more relevant for participants taking cytisine, as its dosing regimen is complex.…”

New Pharmacological Agents to Aid Smoking Cessation and Tobacco Harm Reduction: What Has Been Investigated, and What Is in the Pipeline?

“…Since then a number of studies have demonstrated its efficacy. A pragmatic, open-label, non-inferiority trial with 1310 adult daily smokers, noted that when combined with behavioural support, cytisine promotes continuous abstinence at 6 months to a greater extent than NRT; while a Cochrane systematic review reported that cytisine was four times more effective than placebo [77,78].…”