11 May 2018

Quitting smoking: what’s old is new again

Addiction Clinical

Russian soldiers used this plant to help stave off withdrawal from nicotine addiction during the second world war, and now decades later, Australian researchers are hoping to discover whether the compound holds the key to a cheaper tool to quit smoking. 

Unlike the soldiers who reportedly smoked the plant, manufacturers now extract the active ingredient from the seeds of the Golden Rain acacia and other plants in the Fabaceae family, and turn it into pills for would-be quitters. 

But despite its use in central and eastern European countries since at least the 1960s, cytisine has not been available in countries such as Australia thanks to a lack of high quality research into its effectiveness and safety. 

Now researchers from the National Drug and Alcohol Research Centre (NDARC) hope to change that. Leading the charge is Dr Ryan Courtney, a NSW Cancer Institute research fellow, who plans to pit cytisine against the gold standard, varenicline, for the first time in a randomised controlled trial to determine whether it has a role to play. 

“Both cytisine and varenicline act in a similar way and increase the chances of quitting smoking,” Dr Courtney said. 

“But in terms of high quality research, it wasn’t until this last decade that cytisine had a renaissance period where the western world became interested in studying it.” 

The study, which is planned for almost 1300 current smokers, builds off previous research which found promising results when the plant was compared with nicotine replacement therapies or placebo. 

In a 2014 study published in NEJM, New Zealand researchers found fewer of the 1300 smokers who were randomised into the cytisine group were back smoking in the short and medium term compared with those on nicotine replacement therapies. 

But side effects were slightly higher among those taking cytisine and included reports of problems commonly associated with varenicline, such as nausea, vomiting and sleep disturbances.  

Cytisine, which is sold as Tabex or Desmoxan in some countries, is pharmacologically and structurally similar to varenicline, acting as a partial agonist that binds to the nicotinic acetylcholine receptor. 

The generic drug has a high affinity to the main receptor underpinning the dopamine release that nicotine kicks off in the brain. 

Because the chemical mimics nicotine, users report the severity of withdrawal feelings reduce, alongside a reduction in cravings to smoke. And when smokers do indulge, the reward is dulled. 

Dr Courtney said the cheaper cost of the generic drug compared with varenicline would not only be a relief to the PBS, and possibly drive down prices of both drugs, but would be especially useful in low-and middle-income countries. 

The standard course for cytisine is 25 days, compared with varenicline’s recommended 12 weeks, resulting in a price difference of approximately $25 compared with up to $120 for a patient, he said. 

But public health anti-smoking expert Emeritus Professor Simon Chapman is sceptical of the need for another pharmacological cessation tool, citing the low rates of success these medications have over the long-term in real-world settings. 

Instead, both patients and clinicians needed to be more aware that two-thirds to three-quarters of ex-smokers were able to stop on their own, he said. 

Dr Courtney and his team are currently recruiting trial participants. At the moment, the researchers are only looking for participants within around 100 to 200km of Sydney. Participants would need to be available for telephone interviews and check-ins over a seven month span. 

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