Seventy smokers will be randomized to nicotine doses of either 0.2 or 1 mg per 70 kg body weight. Across 5 test sessions, within each dose group, participants will be randomly assigned to a sequence of 5 treatment conditions: placebo (saline) and 4 different delivery rates of nicotine. In each session, participants will receive either nicotine- or saline-pulsed infusions that will be delivered every 30 seconds for a total of 10 pulsed infusions. While receiving the pulsed infusions, participants will inhale a tobacco-flavored EC without nicotine, which will allow for a closer matching of the sensory aspects of inhaled tobacco use. There are four pulse duration conditions for the nicotine sessions: 2-, 4-, 6- and 8-second pulses. For those assigned to 1.0 mg/70kg nicotine dose, the pulse duration conditions correspond to nicotine delivery rates of 50, 25, 16.6, and 12.5 mcg nicotine/second. For those assigned to 0.2 mg/70 kg dose, the corresponding delivery rates will be 10, 5, 3.3 and 2.5 mcg nicotine/second. Participants in both nicotine dose groups will each have one placebo test session wherein they will receive 10 pulsed-saline infusions.
This project will examine the impact of the nicotine dose and delivery rate on nicotine's abuse potential, versus its potentially beneficial effects on smoking urges and withdrawal. Will use pulsed IV nicotine administration which closely matches nicotine delivery by inhaled tobacco use.