Saliva nicotine as an index of plasma levels in nicotine skin patch users

This study examined whether salivary nicotine concentrations would provide a useful index of plasma concentrations in studies of the effects of transdermal nicotine administration. Twenty-four subject smokers abstained from smoking for 12 h prior to admission to a clinical research unit ward and for 36 h while remaining confined to the ward. Three doses of nicotine skin patches were applied to different groups of subjects, and blood and saliva samples were collected at several time points. Saliva flow was stimulated by three different methods: (a) sucking on a lemon candy, (b) dissolving a sugar cube in the mouth, and (c) chewing on parafilm. Nicotine and cotinine concentrations were measured in both saliva and blood using gas chromatography. There was a high correlation between blood and saliva values of nicotine (r = 0.82). Overall, saliva nicotine concentrations were approximately 8.1 times higher than those of plasma. Saliva and blood cotinine concentrations were also highly correlated (r = 0.94), replicating results of previous studies. Results suggest that saliva nicotine may be a useful marker of nicotine intake during nicotine skin patch treatment. Saliva collection may be advantageous under conditions in which blood collection is impractical and may provide greater sensitivity because of the high concentration of nicotine in saliva relative to that in blood.