Cotinine is an Unreliable Biomarker for Systemic Exposure in Spit Tobacco Users

1. 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

2. Background • 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 Ebbert et al. Addictive Behaviors, in press

3. 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) Ebbert et al. Addictive Behaviors, in press

4. 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

5. 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) Ebbert et al. Addictive Behaviors, in press

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

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

8. Ebbert et al. Addictive Behaviors, in press

9. Conclusions • Nicotine may more accurately reflect systemic exposure to nicotine than cotinine in ST users Ebbert et al. Addictive Behaviors, in press

10. 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 Ebbert et al. Addictive Behaviors, in press

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