Changes in Nicotine Metabolite Ratio among Daily Smokers receiving Treatment for Alcohol Use Disorder

Introduction. Alcohol may influence the nicotine metabolite ratio (NMR), an index of the rate of nicotine metabolism that is associated smoking level and lapses. We examined if NMR changes during alcohol use disorder (AUD) treatment and how changes in NMR relate to reductions in drinking. Methods. Using an observational design, 22 daily smokers (63.64% male, Mage=46.77 (11.37)) receiving AUD treatment completed baseline and follow-up appointments three weeks apart. At each appointment, daily alcohol and cigarette use, salivary and urinary NMR, nicotine exposure via urinary total nicotine equivalents (TNE), and carbon monoxide (CO) were assessed. Multilevel models examined the change over time in NMR and its within-person relations with changes in drinks per week. Sex differences were evaluated. Results. There were significant reductions in both salivary and urinary NMR over time for men (p=.02; p=.01, respectively) but not for women (p=.54; p=.90). There were no changes over time in TNE (p=.09), CO (p=.44), or cigarette use (p=.44), in either sex. Drinks per week were significantly reduced for men (29.12 drink reduction, pp=.80); however, within-person changes in drinking were not associated with changes in salivary or urinary NMR (p=.99; p=.19). Conclusions. The reduction in alcohol use and NMR in men provides indirect support for alcohol increasing NMR. In contrast, the low baseline drinking and lack of alcohol reduction likely underlies the lack of change in NMR in females. Reasons for NMR reductions during AUD treatment and its effects on smoking require further study.