How quickly smokers metabolize nicotine can predict most effective way to quit

A new study has recently revealed that how quickly smokers metabolize nicotine could help in predicting the most effective way to quit smoking.

The findings, from the largest pharmacogenetic study of tobacco dependence treatment to date, reveal that normal metabolizers of nicotine have better quit rates with the non-nicotine replacement therapy drug varenicline (trade name Chantix or Champix) compared with the nicotine patch, whereas slow metabolizers achieve similar quitting success using the nicotine patch but without the side-effects reported with varenicline.

Smokers crave nicotine when their body's nicotine levels drop. However, different people metabolize nicotine at different rates. Nicotine levels in the body drop more quickly in normal metabolizers (60 percent of smokers in the population) so they are more likely to smoke more and find it harder to quit.

Previous research has identified a genetically informed biomarker of nicotine clearance, the nicotine metabolite ratio (NMR) that reflects both environmental and genetic effects on nicotine metabolism. Until now, whether NMR status can be used to optimize treatment choice for individual smokers and improve outcomes has not been tested in a randomized trial.

According to Dr Rachel Tyndale, Head of Pharmacogenetics at the Centre for Addiction and Mental Health at the University of Toronto, Canada, to optimize quit rates for all smokers whilst minimizing side effects, the data suggested that treating normal metabolizers with varenicline and slow metabolizers with the nicotine patch.

It was feasible that a point-of-care blood test to measure the rate at which nicotine was metabolized could be developed and implemented in clinical practice, she further added.

Writing in a linked Comment, Jennifer Ware, Neil Davies, and Marcus Munafo from the University of Bristol in the UK stated that the results reported by Caryn Lerman and colleagues were an important scientific advance. Should the findings be replicated, they might lead to changes in clinical practice through the implementation of prescriptions stratified on the basis of a biomarker test

However the extent to which tailoring treatment by a biomarker such as NMR was a cost-effective approach would depend on doing a full health economic assessment, including consideration of the relevant national context, which would also have to consider the effect of warnings stipulated by national regulatory bodies on prescribing rates of varenicline, they further concluded.

The study is published in The Lancet Respiratory Medicine journal.