Nicotine levels after IV nicotine and cigarette smoking in men.

There has been considerable interest in the pharmacodynamics and pharmacokinetics of nicotine and the influence of different routes of administration. However, these variables are often examined in separate studies, and there is less information about the temporal relation between subjective reports and plasma nicotine levels. This study examined the time course and magnitude of plasma nicotine levels and reports of subjective "high" in nicotine-dependent men after 12 or more hrs of abstinence. The effects of two doses of IV nicotine and two doses of nicotine from cigarette smoking were compared, and samples were collected at 2-min intervals. Plasma nicotine levels after smoking a high-nicotine cigarette were significantly greater than after either dose of IV nicotine (p < .001). However, Visual Analog Scale (VAS) ratings of "high" after both doses of IV nicotine and smoking a high-nicotine cigarette did not differ significantly, and followed a similar time course. After smoking a low-nicotine cigarette, VAS ratings of "high" were significantly lower than after either IV nicotine dose or smoking a high-nicotine cigarette (p < .001). Peak levels of "high" were reported within 2 min after IV nicotine administration and the onset of cigarette smoking. Then "high" ratings abruptly decreased, while plasma nicotine rose to peak levels within 4 to 6 min after IV nicotine and 12 to 14 min during cigarette smoking. Plasma nicotine levels did not appear to determine the magnitude or time course of subjective effects under these conditions.