Cytisine, a quit-smoking drug that costs just $15 for a four-week course, was more effective than placebo at preventing smoking at 12-month follow-up, data indicate.

In a randomized, double-blind, placebo-controlled clinical trial conducted in Poland involving 740 participants, 8.4% assigned to cytisine remained abstinent at one year vs. 2.4% of participants assigned to a placebo group (P=0.001), Robert West, PhD, of the University College London and colleagues reported in New England Journal of Medicine.

Although popular in Eastern Europe since the communist era, cytisine (Tabex, Sopharma AD), a partial agonist at alpha-4/beta-2 nicotinic acetylcholine receptors extracted from the seeds of Golden Rain acacia, had not undergone a large randomized trial until now.

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Despite the significant findings, abstinence rates with cytisine were low compared with approved smoking cessation drug varenicline (Chantix), which demonstrated 12-month abstinence rates above 20% in clinical trials vs. 8% to 10% with placebo.

But varenicline and other established nicotine pharmacotherapies often cost hundreds of dollars and are too expensive for the majority of the world’s 1 billion smokers, whom live in countries where average household incomes are less than $200 per week, according to background information in the study.

“The lower price of cytisine as compared with that of other pharmacotherapies for smoking cessation may make it an affordable treatment to advance smoking cessation globally,” West and colleagues wrote.

They randomly assigned 740 participants in equal numbers to cytisine tablets 1.5 mg or placebo for 25 days. All participants smoked at least 10 cigarettes per day at baseline and stated a desire to quit.

Cytisine was administered on a tapered schedule, in line with historic treatment regimens in Eastern Europe, consisting of six tablets per day for the first three days, five tablets per day on days four to 12, four tablets per day on days 13 through 16 and so on until the final five days, when participants were taking two tablets per day.

Participants received minimal counseling “to simulate, as much as possible, what might happen in a routine clinical situation,” the researchers wrote.

At six- and 12-month follow-up visits conducted after treatment ended, participants discussed smoking behaviors and adverse events, and the researchers measured carbon monoxide in breathe to verify cessation.

Although cytisine was not as effective as varenicline at 12-month follow up, the researchers pointed out that the rate ratio for abstinence among patients assigned to cytisine vs. placebo was 3.4, which was higher than rates observed with varenicline and other pharmacotherapy options.

“Combining cytisine with more intensive behavioral support may result in higher absolute quit rates,” the researchers wrote. “Also, the treatment period was only four weeks, as compared with eight weeks for nicotine-replacement therapy and 12 weeks for varenicline, and it is possible that efficacy could be improved by a longer regimen.”

Adverse events occurred more frequently overall in the cytisine group than in the placebo group, but were not statistically significant, according to the researchers. The most common adverse events include gastrointestinal disorders, consisting mostly of stomachache, dry mouth, dyspepsia and nausea, occurring in 13.8% of the cytisine group vs. 8.1% of the placebo group (P<0.05).

Psychiatric events occurred in 4.6% of patients assigned to cytisine vs. 3.2% of the placebo group, a measure of particular concern, as varenicline has been associated with suicidal thoughts.

The researchers emphasized that the current study was not large enough to detect other uncommon adverse events and added that the drug should continue to be monitored for safety.

West R et al. N Engl J Med. 2011; 365:1193-1200.