New Zealand researchers have shown that a low-cost, Soviet-era quit-smoking pill is more effective than nicotine-replacement therapy.
Forty per cent of smokers who took the cytisine pills had been "continuously abstinent" in the month after their nominated quit day, significantly more than the 31 per cent on NRT. Continuous abstinence is defined as smoking no more than five cigarettes.
The trial's more than 1300 participants were recruited from among callers to the national stop-smoking Quitline.
The results of the Auckland University trial are published today in a leading international medical publication, the New England Journal of Medicine.
Made in Poland and Bulgaria, cytisine pills have been available since the 1960s in Central and Eastern Europe, where they are sold on prescription or as an over-the-counter medicine. Marketed as Tabex and Desmoxan, they are available from international websites but are not permitted to be sold in New Zealand as they are not registered with the Health Ministry as a medicine.
Cytisine, obtained from the golden rain tree, is a similar type of drug to the quit-smoking medication Champix.
"To the brain, cytisine looks a little like nicotine and so it works to alleviate any urges to smoke and reduces the severity of nicotine withdrawal symptoms," said Dr Natalie Walker, one of the Auckland University researchers.
Researchers have called for medicines regulators to license cytisine partly because it is cheap; sold for as little as $1 a day for the 25-day course, it is much cheaper than other smoking-cessation drugs. In New Zealand the price difference may be of greater interest to the Government than to individual smokers because a range of quit-smoking products are subsidised by taxpayers. However, researchers believe there is value in having an extra product available because some but not others might work for individual smokers.
"We have asked the manufacturers if they can approach our Government," Dr Walker said. "My understanding is that they have had some initial discussions with [drugs regulator] Medsafe."
"The real appeal is for low- and middle-income countries because they can't even afford nicotine replacement therapy but they could afford cytisine."
In the trial, the cytisine-related 6-month continuous abstinence rate was 22 per cent, compared with 15 per cent for the NRT users.
When the quitting results were analysed by gender, it was found that for women, cytisine was better than NRT, although for men the two types of medicine were equally effective. The reasons for the gender difference are not known. The researchers say it could be from chance, but warrants further investigation, "since several reviews of nicotine-replacement therapy have reported lower quit rates in women than in men, possibly as a result of biologic and psychosocial differences".
The journal paper also says the median time to resumption of smoking was significantly longer, at 53 days, on cytisine, compared with 11 days on NRT.
Dr Walker said that even if cytisine users didn't quit, they enjoyed smoking less and smoked fewer cigarettes.
The rate of adverse side effects was greater for cytisine, but Dr Walker said they were fairly minor and included nausea and sleep disturbance.