Cotinine is an Unreliable Biomarker for Systemic Exposure in Spit Tobacco Users Jon O. Ebbert, MD, MSc Lowell C. Dale, MD Liza Nirelli Darrell Schroeder, MS Thomas Moyer, PhD Richard D. Hurt, MD Mayo Clinic Rochester, MN Jon O. Ebbert, MD, MSc Lowell C. Dale, MD Liza Nirelli Darrell Schroeder, MS Thomas Moyer, PhD Richard D. Hurt, MD Mayo Clinic Rochester, MN

Ebbert et al. Addictive Behaviors, in press Background Spit tobacco (ST) users absorb nicotine both through the buccal mucosa and the gastrointestinal tract Spit tobacco (ST) users absorb nicotine both through the buccal mucosa and the gastrointestinal tract (Benowitz, 1989) Swallowed nicotine is known to enter the portal circulation through the small intestine and undergo first-pass metabolism by the liver Swallowed nicotine is known to enter the portal circulation through the small intestine and undergo first-pass metabolism by the liver Spit tobacco (ST) users absorb nicotine both through the buccal mucosa and the gastrointestinal tract Spit tobacco (ST) users absorb nicotine both through the buccal mucosa and the gastrointestinal tract (Benowitz, 1989) Swallowed nicotine is known to enter the portal circulation through the small intestine and undergo first-pass metabolism by the liver Swallowed nicotine is known to enter the portal circulation through the small intestine and undergo first-pass metabolism by the liver

Ebbert et al. Addictive Behaviors, in press Background Nicotine entering the liver through the portal circulation is converted to cotinine and other metabolites before reaching the systemic circulation Cotinine is pharmacologically inactive Contributes to the higher serum cotinine concentrations observed in ST users compared with cigarette smokers (Benowitz, 1989) Nicotine entering the liver through the portal circulation is converted to cotinine and other metabolites before reaching the systemic circulation Cotinine is pharmacologically inactive Contributes to the higher serum cotinine concentrations observed in ST users compared with cigarette smokers (Benowitz, 1989)

Ebbert et al. Addictive Behaviors, in press Hypothesis Cotinine may be an inaccurate measure of systemic nicotine exposure in ST users if cotinine positively correlates with the amount of tobacco juice that is swallowed.

Ebbert et al. Addictive Behaviors, in press Methods Used data obtained from 68 daily ST users enrolled in a randomized, controlled clinical trial of bupropion for ST users (Dale, 2002) Correlated baseline serum nicotine and cotinine concentrations with clinical measures of ST dependence Items from the modified FTQ for ST users (Boyle, 1995) Used data obtained from 68 daily ST users enrolled in a randomized, controlled clinical trial of bupropion for ST users (Dale, 2002) Correlated baseline serum nicotine and cotinine concentrations with clinical measures of ST dependence Items from the modified FTQ for ST users (Boyle, 1995)

Ebbert et al. Addictive Behaviors, in press Spit Tobacco & Bupropion: Pilot Study

Ebbert et al. Addictive Behaviors, in press Table 2. Association of Tobacco Usage Variables with Serum Nicotine and Cotinine

Ebbert et al. Addictive Behaviors, in press

Conclusions Nicotine may more accurately reflect systemic exposure to nicotine than cotinine in ST users

Ebbert et al. Addictive Behaviors, in press Clinical Implications Nicotine may be preferred when accurate measures of systemic exposure to nicotine are needed Tailoring nicotine patch dose Nicotine may be preferred when using biomarkers to predict: Withdrawal Abstinence outcomes Nicotine may be preferred when accurate measures of systemic exposure to nicotine are needed Tailoring nicotine patch dose Nicotine may be preferred when using biomarkers to predict: Withdrawal Abstinence outcomes

Ebbert et al. Addictive Behaviors, in press Clinical Implications Nicotine may be preferred when developing clinical scales for nicotine dependence in ST users