Cytisine was more effective than nicotine replacement therapy at helping adults quit smoking, with effect sizes similar to those reported in trials of varenicline, according to a report published online Dec. 18 in the New England Journal of Medicine.
Cytisine is a plant-based alkaloid that, like varenicline, is a partial agonist of nicotinic acetylcholine receptors. It remains relatively unknown outside of Eastern Europe, where it has been used successfully for 50 years, the study authors noted, even though it has proved effective there and is inexpensive. Some in the medical community have called for it to be licensed worldwide as a smoking-cessation aid.
The researchers directly compared cytisine with nicotine replacement therapy in an open-label, randomized, noninferiority trial in New Zealand.
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A total of 1,310 adults who contacted New Zealand’s Quitline for assistance in smoking cessation were randomly assigned in equal numbers to receive either 25 days’ worth of cytisine tablets or 8 weeks of nicotine replacement therapy (patch and/or gum) plus brief behavioral counseling. They were followed for 6 months.
Cytisine proved significantly superior to nicotine replacement therapy: 40% of patients who took cytisine reported continuous smoking abstinence at 1 month, compared with 31% of those in the control group, said Natalie Walker, Ph.D., of the National Institute for Health Innovation, University of Auckland (New Zealand), and her associates.
Patients in the cytisine group also reported fewer symptoms of tobacco withdrawal than those in the nicotine replacement group.
Among study participants who resumed smoking after completing treatment, the median time to relapse was significantly longer with cytisine (53 days) than with nicotine replacement (11 days). People in the cytisine group also reported smoking fewer cigarettes per day and found smoking less rewarding than it had been before the study, the investigators said (N. Engl. J. Med. 2014;371:2353-62).
However, self-reported adverse events – most commonly nausea, vomiting, and sleep disorders – were almost twice as frequent in the cytisine group as in the control group. Most adverse events were mild to moderate in severity, and only 5% of the study population discontinued treatment because of adverse events.
The findings show that cytisine “is an effective smoking cessation aid for use as a first-line treatment for tobacco dependence,” Dr. Walker and her associates said.
The Health Research Council of New Zealand supported the study. Sopharma, a manufacturer of cytisine (Tabex), supplied the agent at no cost. Dr. Walker reported having no financial conflicts of interest; one of her associates reported receiving lecture fees from Johnson & Johnson and grant support from Pfizer.