No increased levels of the nicotine metabolite cotinine in smokers with schizophrenia

The prevalence of smoking cigarettes has repeatedly been found to be greater in schizophrenia as compared with other psychiatric patients and the general population. Patients with schizophrenia have been found to engage in heavy smoking and consumption of higher doses of nicotine, probably by deeper inhalation of cigarettes. The aim of the current study was to assess nicotine exposure through smoking by measuring urinary cotinine, the major nicotine metabolite, in a group of smokers from Greece of smokers with schizophrenia and smokers from the general population. Participants were current smokers and belonged to one of two groups: 35 patients with schizophrenia and 48 healthy controls matched in age, education, and gender. The quantitative analysis of cotinine, the major metabolite of nicotine, in urine samples was performed by a modified high performance liquid chromatography (HPLC). Patients with schizophrenia who smoke presented a significantly larger time interval between last cigarette smoked and urine sample collection, as well as a significantly higher average number of cigarettes consumed daily than normal smokers. Urinary cotinine levels of patients with schizophrenia who smoke did not significantly differ from that of normal smokers when adjusted for average number of cigarettes per day and time interval between last cigarette smoked and urine collection. These results suggest that patients with schizophrenia did not present higher nicotine exposure through smoking compared with smokers from the community. The pharmacokinetic or pharmacodynamic properties of nicotine, as well as patient medications of the patients may explain our findings.