Sources of variability in nicotine and cotinine levels with use of nicotine nasal spray, transdermal nicotine, and cigarette smoking

AIMS: Nicotine nasal spray and transdermal nicotine are effective aids to smoking cessation, and are being evaluated for treatment of other medical diseases. Wide variation in levels of nicotine and its metabolite, cotinine, have been observed with such therapies. This study aimed primarily to assess sources of individual variability in nicotine and metabolite plasma levels from these dosing syste…