Previous studies of nicotine metabolism and cessation treatment have examined a proxy for CYP2A6 activity, Nicotine Metabolite Ratio (NMR), the ratio of two stable nicotine metabolites, cotinine: 3-hydroxycotine, measured in the blood of current smokers (12-16). We have recently developed another predictive model of nicotine metabolism based on CYP2A6 genotype. CYP2A6 haplotypes included in this model explained 70% (R2=0.7) of the variance in metabolism of oral nicotine among European Americans. Metabolism estimates predicted by the model were significantly correlated with self-reported cigarettes smoked per day (CPD) (7, 11) and exhaled carbon monoxide (unpublished data).
