Nicorette lozenge

On separate study visits approximately one week apart, participants were administered either 2-mg nicotine (Nicorette Lozenge, GlaxoSmithKline, Brentford London) or placebo (Tums antacid, GlaxoSmithKline, Brentford London) lozenges. A 2-mg dose of nicotine was used because it delivers the total amount of nicotine typically received from smoking a single cigarette (16 (link)–18 (link)). Lozenges were administered in a randomized, counterbalanced, and double-blind manner. An hour before entering the scanner, participants placed the lozenge inside their mouth, next to their cheek, and allowed it to dissolve completely without chewing. We measured cotinine to confirm the presence and absence of nicotine absorption on nicotine and placebo study days respectively (19 (link)).

Participants received a 2-mg nicotine lozenge or placebo lozenge 1 hour prior to scanning in a double-blind randomized cross-over design with each participant completing the nicotine and placebo conditions on average 10.5 days apart (one lozenge type per study visit) (Janes et al., 2018 (link)). The nicotine lozenge (Nicorette Lozenge, GlaxoSmithKline, Brentford London) and placebo (Tums antacid, GlaxoSmithKline, Brentford London) were both mint flavored and similar in size, shape, and color. The lozenges dissolved next to the cheek in approximately 15 minutes without chewing. Plasma nicotine levels for the 2-mg lozenge peak at 1 hour with a 2.3-hour half-life (Choi et al., 2003 (link)), and scanning took place within this window. This dose yields approximately 1-mg of systemic nicotine (Choi et al., 2003 (link)) and is similar to smoking one cigarette (Benowitz and Jacob, 1984 (link)). The resting state scan was the first functional sequence run, and resting state instructions for the non-smoker and smoker cohorts were identical. Blood draws were collected immediately post scanning to quantify the concentration of cotinine, the main metabolite of nicotine. One female and two male participants were unable to provide serum samples, thus urine measurements were taken to verify the effect of the nicotine lozenge.