The effects of supplementary nicotine in regular cigarette smokers.

Blood nicotine levels were measured in eight subjects over a 5-week period, while smoking normally, while smoking and chewing gum containing 2 mg nicotine, and while smoking and chewing placebo gum. Despite a small but significant rise in blood nicotine levels during the period of the nicotine gum chewing (mean 35.3 ng/ml) compared with placebo (mean 28.9 ng/ml) and control (mean 26.3 ng/ml), cigarette consumption butt lengths, filter nicotine and blood carboxyhaemoglobin levels did not change indicating that there had been no significant changes in smoking patterns. The reasons for this failure to demonstrate an effect are discussed. It is concluded that the dose of nicotine used was probably not adequate to produce an effect.