15 August 2012
Scientists at British American Tobacco have compared nicotine absorption from different commercially available snus products and directly compared the results with those from a cigarette and a high-dose nicotine chewing gum intended for smoking cessation treatment. This is the first time that such a comparison has been done.
‘There has been a scientific need to update the understanding of different tobacco products in terms of nicotine absorption,’ said Dr Chris Proctor, Chief Scientific Officer at British American Tobacco. ‘This information shows clearly that the nicotine gum resulted in substantially lower systemic nicotine exposure than either the cigarette or any of the forms of snus tested.’
Snus is a heat-treated, finely-ground, moist tobacco sold either loose or in pouches. There is increasing consensus that snus represents substantially lower overall health risks than cigarettes. The findings of a recent study indicates that, for some smokers, switching to snus can be an effective way of quitting smoking (Harm Reduction Journal, 2012, 9:10).
The results of this study, which are reported in Nicotine & Tobacco Research show that the maximum total absorption of nicotine from snus is greater than that from a cigarette. Although the nicotine is absorbed more quickly from a cigarette, the maximum total absorption from one snus portion is substantially higher than that from one cigarette. The total absorption of nicotine from snus is determined by quantity of tobacco and nicotine content.
This study, conducted in Sweden, was designed to evaluate five different commercially available tobacco products: two 1g snus pouches with different nicotine contents; two different weights of loose snus (1g and 2.5g); a commercially available cigarette and an over-the-counter nicotine chewing gum. Twenty healthy adults, who already consumed snus daily and smoked cigarettes from time to time, tested each of the products on separate occasions. Snus was used for an hour (consistent with actual product use), the nicotine gum for 30 minutes and the cigarette for 5 minutes. To calculate nicotine absorption, blood samples were taken at intervals over 120 minutes and the nicotine concentration in blood plasma measured (clinical trial registration number: ISRCTN11703777).
The absorption of nicotine from a product was determined by the maximum concentration of nicotine reached in the plasma and the total plasma nicotine concentration over 2 hours. The results show that, for the snus products, both these measurements are dependent on the total nicotine content of the product. Nicotine absorption, which is highest for the product containing the most nicotine, is ranked as follows: 2.5g of loose snus (containing 27.1mg of nicotine) > 1g of pouched snus (containing 14.7mg of nicotine) > 1g of loose snus (containing 10.8mg of nicotine) = 1g of pouched snus (containing 10.7mg of nicotine) > nicotine gum (containing 4.2 mg of nicotine).
“The similar nicotine absorption for 1g portions of loose and pouched snus containing approximately 11mg of nicotine indicate that absorption kinetics were dependent on quantity of tobacco by weight and total nicotine content rather than product format,” says Helena Digard, lead author of the study.
Genotyping was conducted on the blood samples to identify participants that metabolise nicotine quicker than others, but metabolic status was found to have no impact on the interpretation of the pharmacokinetic data. Used and unused snus and gum samples were analysed for nicotine. The mean percentage of nicotine extracted was highest for the nicotine gum (63%) but only between 24% and 32% for the snus products, suggesting that nicotine in snus may be less bioavailable than in gum. In addition, data for the two different nicotine levels in the pouched snus products indicate that its relationship with absorption is not proportional.
The data also show that nicotine is continually absorbed from the snus portions over the entire hour they are used. The researchers do note, however, that the study is not representative of all snus users as it does not take into account the potential of the swallowing of some loose snus, moving snus products around the mouth, and other behaviours that could affect nicotine absorption.
NOTES TO EDITORS
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