Modelling nicotine intake in smokers and snuff users using biological fluid nicotine metabolites.

Data from two clinical studies involving smokers and snuff users were analysed to address the estimation of nicotine intake using urinary and salivary nicotine metabolites. Comprehensive regression modelling is performed to determine which combinations of urinary nicotine metabolites provide better estimation of nicotine intake in these subjects than the predominant practice of basing nicotine intake on urinary cotinine analysis alone. Within-subject and between-subject variability is examined with regard to reliability of measurement and replicate sampling.