To examine the effects of varenicline on the subjective, physiological and cognitive responses to intravenous nicotine. Varenicline is a partial nicotine agonist and it is approved as a treatment for smoking cessation. We predict that varenicline treatment will modify subjective, physiological and cognitive responses to IV nicotine.
This will be a 2-4 week double-blind, placebo-controlled study. Twenty four male and female smokers will have two 4-day treatment periods, in which they will be randomized to varenicline (1 mg/day) or placebo. During the first 3 days of each treatment period, smokers will have daily clinic visits and receive their study medication. On Day 4, subjects will come to the laboratory, where they will receive ascending doses of intravenous (IV) nicotine (0.1, 0.4, and 0.7 mg per 70kg). This procedure will allow accurate assessment of varenicline effects on the subjective, physiological and cognitive responses to nicotine. Following a washout period, subjects will be crossed over to the alternative treatment.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
37
Varenicline (1 mg per day) given for 4 days prior to laboratory session
Sugar Pill
IV Nicotine given during the laboratory session following 4 days of exposure to the study medication (varenicline or placebo). This nicotine was given during each laboratory session which followed the 4 days of exposure to either placebo then varenicline or varenicline then placebo.
Veterans Affairs Hospital
West Haven, Connecticut, United States
Subjective Responses to Intravenous Nicotine
The Drug Effects Questionaire( DEQ) is a 7-item psychometric that measures the following subjective categories: 'drug strength',' high', 'feels stimulated', 'good effects', 'bad effects', 'head rush', and 'like the drug'. Smokers rated each item on a 100 millimeter scale from "not at all" (a score of 0) to "extremely" with a maximum score of 100.
Time frame: 30 minutes after each nicotine infusion
Mean Reaction Time (RT) on Modified Stroop Task.
A Modified stroop task was used to assess attentional responses to smoking and negative affect cues. Cues were presented as blue, red or green text. Subjects completed 2 counterbalanced blocks (60 trials per block). One block contained smoking cues and neutral cues. The other block contained negative affect cues and a different set of matched neutral cues. The 2 blocks were administered twice during each experimental session - prior to nicotine infusion, and 30 mins after the last nicotine infusion (2 hrs and 45 mins after medication dosing). The Stroop effect is a differential RT when identifying the colors of words presented as neutral cues vs. emotional cues (i.e. smoking or negative affect cues).
Time frame: pre-nicotine, and 30 min after last nicotine infusion (Post-Nicotine)
Cotinine Levels
Subject Cotinine Levels before each laboratory session.
Time frame: Before each laboratory session on day 5
Heart Rate
The average peak change (change score = maximum post dose score minus predose baseline) in heart rate was calculated.
Time frame: 30 minutes after each nicotine infusion
Changes in Systolic and Diastolic Blood Pressure
The average peak change (change score = maximum post dose score minus predose baseline) in systolic and diastolic blood pressure after nicotine infusion.
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Time frame: 30 minutes after each nicotine infusion