Biomarkers of Nicotine Exposure

This section focnses on the nse of nicotine and cotinine and other tobacco alkaloids as biomarkers of tobacco exposure. Other potential biomarkers of exposure to the particulate or gas phase of tobacco smoke are described in the review papers cited above. 

The relationship between nicotine intake and steady state cotinine blood levels can be expressed in the following way, based on steady state exposnre conditions Dnic = CLcot X CcoT f, where Dnic is the intake (dose) of nicotine, CLcot is the clearance of cotinine, Ccot is the steady state blood concentration of cotinine and f is the fraction of nicotine converted to cotinine. On rearranging the equation, Dnic = (CLcot f) x Ccot = K x Ccot where K is a constant that converts a given blood level of cotinine to nicotine intake. On average, K = 0.08 mg 24h ng ml (range 0.05-1.1, CV = 21.9%). Thus, a cotinine level of 30 ng ml in blood corresponds on average to a nicotine intake of 24 mg per day. 

Biomarker Precursor Specimen Tobacco specific Other sources 

Nicotine Nicotine Blood, urine, saliva, hair 1-2 h Yes Nicotine replacement products 

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An understanding of the pharmacology of nicotine and how nicotine produces addiction and influences smoking behavior provides a necessary basis for therapeutic advances in smoking cessation interventions. This chapter provides a review of several aspects of the human pharmacology of nicotine. These include the presence and levels of nicotine and related alkaloids in tobacco products, the absorption of nicotine from tobacco products and nicotine medications, the distribution of nicotine in body tissues, the metabolism and renal excretion of nicotine, nicotine and cotinine blood levels during tobacco use or nicotine replacement therapy, and biomarkers of nicotine exposure. For more details and references on the pharmacokinetics and metabolism of nicotine, the reader is referred to Hukkanen et al. (2005c). 

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