Natalie Walker et al, Cytisine versus Nicotine for Smoking Cessation. The New England Journal of Medicine, December 18th, vol 371, no 25. 2014
This is the first study performed to test the effectiveness of Cytisine compared with nicotine replacement therapy (patches plus gum and loxenges). The researchers recruited smokers who had expressed a desire to quit smoking and had contacted a Quitline in New Zealand.
Cytisine is a plant-based alkaloid found in members of the Leguminosae family. Cytisine is a partial agonist of nicotinic acetylcholine receptors meaning that it acts upon the brain in a similar manner as nicotine. It is a generic agent currently manufactured by Sopharma as Tabex and by Aflofarm Pharma as Desmoxan. It has been available both with and without prescription for smoking cessation since the 1960s, largely in Eastern Europe. Cytisine is associated with no significant increase in serious adverse events when compared with sham treatments , however nausea and gastrointestinal symptoms are more common, albeit mild and well tolerated. Cytisine is significantly cheaper than other smoking cessation therapies such as nicotine replacement therapy or varenicline.
Results of the study
In this study by Natalie Walker and colleagues smokers were randomly assigned to two groups, they received either Cytisine (in tablet format) for 25 days or Nicotine replacement therapy for 8 weeks. Both groups also received brief behavioural support via the Quitline service. 1310 regular smokers were entered into the study. About 12% of participants in both groups dropped out of the study. At one month smoking cessation was significantly greater in the cytisine group compared with the nicotine group (40 % versus 31%). The researchers followed participants up for 6 months and at that time 22 % of people in the cytisine group were still successful quitters compared with 15% in the nicotine group. Self-reported adverse events over 6 months occurred more frequently in the cytisine group compared with the nicotine, these were mainly nausea, vomiting and sleep disorders but were generally well tolerated by the study participants.
When combined with brief behavioral support, cytisine was more effective in helping smokers quit smoking than nicotine replacement therapy but it was associated with a higher frequency of self-reported adverse events. Combined with behavioural support cytisine may provide a real cost effective treatment for smoking cessation.
There are some limitations of this study, primarily the method of delivery of the two treatments differed, participants were sent redeemable vouchers for the purchase of patches / gum but were required to collect them from a local pharmacy, whereas the cytisine group were sent the tablets directly. In addition, the measurement of smoking cessation was determined by self report and not by objective measures such as carbon monoxide measures.
However, the study is strengthed by its large sample size and randomisation. This is an important study when considering our arsenal of therapy aimed at helping smokers quit, in particular since cytisine is a relatively inexpensive treatment and available without prescription this treatment could offer help to large numbers of people.