Figure 4. Behavioral economic demand curves derived from the CPT. Note the double logarithmic coordinates. Data points show the median number of cigarettes purchased for each group at each price prior to (study Day 1, upper panel) and after (study Day 7, lower … The PRT showed a significant main effect of Time for puffs earned selleck chem (F(1, 44) = 25.2, p < .0001), reflecting a reduction in smoking self-administration in the laboratory from study Days 1�C7, but no effect of Medication or Medication �� Time interaction was found. Mean (SD) total responses (mouse clicks) on the task decreased from 2,380 (2,960) to 1,207 (3,633) for the placebo group and from 5,422 (8,101) to 3,416 (8,350) for the varenicline group on study Days 1 and 7, respectively. This corresponds to a mean decrease of 1.8 (2.
0) puffs earned for the placebo group versus 2.0 (3.0) for the varenicline group following medication induction. Subjective Effect Assessments Subjective assessments of withdrawal, craving, mood, side effects, and quit confidence administered at all study visits were not sensitive to medication effects. These questionnaires consistently showed significant main effects of Time, with craving, withdrawal, and negative mood ratings decreasing over time in both groups. However, significant main effects of Medication were only observed for loss of balance on the Medication side effects questionnaire (F(1, 45) = 5.5, p < .05; varenicline > placebo), for ��upset�� (F(1, 45) = 9.7, p < .05), ��ashamed�� (F(1, 45) = 6.4, p < .05), and ��jittery�� (F(1, 45) = 10.0, p < .
05) on the PANAS (varenicline < placebo), and for ratings of ��how pleasant a cigarette would be right now�� (F(1, 45) = 4.2, p < .05) on the Schuh�CStitzer questionnaire (varenicline < placebo). Medication Compliance Urine toxicology testing on study Days 7, 21, and 35 suggested a high rate of medication compliance for those randomized to receive varenicline. All samples tested had measurable amounts of varenicline but considerable variability within and across participants was noted. Mean (SD) concentrations of urinary varenicline were 371 ng/ml (263) on Day 7, 1,017 (1,052) on Day 21, and 570 (612) on Day 35. Discussion Relapse Prevention The current study used a prospective between-subjects design to demonstrate the relapse prevention effects of varenicline following experimental exposure to a smoking lapse.
Varenicline slowed rates of relapse (Figure 1), reduced objective biomarkers of smoking (Figure 2), and improved rates of abstinence at 4-weeks postlapse (Table 2) in this short-term model of smoking cessation, GSK-3 lapse, and relapse. The percentage of participants remaining continuously abstinent (COT verified) at the end of the 4-week quit attempt was 40% for the varenicline group versus 14% in the placebo group. These rates are remarkably similar to abstinence rates produced in much lengthier clinical trials of varenicline as a smoking cessation aid (Gonzales et al.