Learning Objectives: To identify the limitations of cotinine as a biomarker of systemic nicotine exposure in spit tobacco users.
Abstract:
Problem/Objective: Unlike cigarette smokers, spit tobacco (ST) users absorb a significant amount of nicotine through the gastrointestinal tract while swallowing tobacco juice. The majority of the absorbed nicotine is rapidly converted to cotinine during first-pass hepatic metabolism. This process potentially compromises the utility of cotinine as a biomarker for systemic nicotine exposure in ST users.
Methods: To investigate this question, we correlated serum nicotine and cotinine concentrations with clinical measures of ST use in 68 daily ST users enrolled in a non-nicotine pharmacologic intervention trial.
Results: A higher number of cans/pouches used per week (Spearman r=0.42; p < .001) and a higher number of dips per day (r=0.35; p=.004) were univariately associated with a higher serum cotinine concentration. An increased frequency of swallowing tobacco juice was an independent predictor of a higher serum cotinine concentration in both univariate (r=0.26; p=.032) and multivariate analyses (p=.007). A higher number of dips per day (r=0.27; p=.038) and a higher number of cans/pouches used per week (r=0.39; p=.001) were univariately associated with a higher serum nicotine concentration. Serum nicotine concentrations were not correlated with a higher frequency of swallowing. Discussion: In the absence of a reliable way to measure frequency of swallowing, we conclude that cotinine should not be used for guiding clinical decisions that depend upon a precise quantification of systemic nicotine exposure, such as tailored nicotine replacement therapy.
Cotinine San Fran.pps (295.0 kb)
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