A SMOKER'S chances of quitting can be predicted from the way the body processes nicotine, a study has found.
Measuring the rate of nicotine breakdown can help determine the best strategy to be adopted for a particular individual, experts believe.
The research shows that "normal" nicotine metabolisers - who make up 60pc of smokers - might be better off using a drug than nicotine patches.
Those classified as "slow" metabolisers achieve similar quitting success with a patch.
Scientists compared the effectiveness of nicotine patches or the drug varenicline in a study involving 1,246 smokers who wanted to quit.
Of the participants, 662 were slow metabolisers of nicotine and 584 normal metabolisers.
Professor Caryn Lerman, from the University of Pennsylvania, who co-led the study published in The Lancet Respiratory Medicine journal, said: "As many as 65pc of smokers who try to quit relapse within the first week.
"Our findings show that matching a treatment based on the rate at which smokers metabolise nicotine could be a viable clinical strategy."
Nicotine cravings occur when levels of the alkaloid compound drop, taking away the "feel good" sensation it imparts on reward centres in the brain.
A blood marker of nicotine clearance known as the nicotine metabolite ratio (NMR) can provide a measure of the rate of nicotine loss, depending on a person's genetic make-up.
Nicotine levels in the body drop quicker in normal metabolisers than in slow metabolisers.
The study showed that after 11 weeks of treatment, normal metabolisers taking varenicline were twice as likely not to be smoking as those using a nicotine patch.
They were also significantly more likely to still be avoiding tobacco six months later.