Nicotine gum: chew rate, subjective effects and plasma nicotine.

Two studies were conducted to assess the effects of varying the rate at which single pieces of nicotine gum (4 mg) were chewed. In each study, six cigarette-deprived volunteers were tested during four sessions. In each session, they were required to chew the gum for 10 min at varying rates; a variety of self-report and physiologic responses were recorded before and after chewing. All chewed gum was analyzed for amount of nicotine extracted, and blood samples were collected for nicotine analysis. Additionally, in Experiment 2, a measure of masticatory pressure was employed to assess the intensity of chewing and to empirically verify the number of chews. In both studies, we found a weak, but direct, relation between chew rate and the amount of extracted nicotine. Experiment 2 revealed a probable cause of the weaker than expected "dose-effect" function: subjects showed compensatory changes in behavior by chewing slower than instructed in the high rate conditions, and by chewing faster than instructed in the low rate conditions. Thus, despite instructions to vary chew rates across an 8-fold range, actual chew rate varied by only 2.2-fold. Intensity of chewing remained constant across conditions. Taken together, the findings suggest that rate of chewing nicotine gum can make a difference in the amount of nicotine extracted from the gum; however, compensatory changes in chew rate may attenuate attempts to systematically vary nicotine dose in this manner.