Effectiveness of GSK598809, a Selective D3 Antagonist, Added to CBT and NRT for Smoking Cessation and Relapse Prevention

Phase 2

Completed

Brief Summary: The purpose of this research study is to find out if an investigational drug, GSK598809 can help people who have very recently quit smoking; the investigators want to find out if continuing to take GSK598809 over six weeks can help prevent smokers from relapsing. To relapse means you "fall back" into smoking again after quitting. The investigators also want to find out if GSK598809 is safe to take without causing too many side effects.

Detailed Description: We propose to conduct a first test of the effect of the dopamine D3 receptor antagonist, GSK598809, on smoking behavior when treatment is started immediately following the quit date. To do this, we propose to conduct a 10-week, double-blind, placebo-controlled, proof of mechanism study in 90 adult smokers. Participants will complete baseline evaluations. They will receive manualized cognitive behavioral therapy, beginning prior to the quit date, and will set a quit date for the day before their week 2 study visit. They will be given short acting NRT (gum or lozenge) to use on their quit date. They will be asked to arrive for the week 2 visit with 18-24 hours abstinence and an expired air CO ≤ 10ppm. Those who do so will be randomly assigned to receive double blind GSK598809 or identical placebo for six weeks. Participants will begin double blind GSK598809 or placebo, both in conjunction with prn NRT up to 8 mg per day for two weeks. Participants will then continue double blind GSK598809 or placebo in the absence of NRT for 4 more weeks. At the end of this period (week 8 of the study), participants will then be followed 2 weeks after discontinuation of double blind treatment to complete the 10 weeks of the study.

Recruitment & Eligibility

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	Placebo
GSK598809	GSK598809	Active medication

Primary Outcome Measures

Name	Time	Method
4-week, Continuous Tobacco Abstinence at the End of the 6-week, Double Blind, Treatment Phase	Week 8 of the study	The hypothesis is that those assigned to GSK598809 will demonstrate a higher rate of biochemically-verified, 4-week, continuous tobacco abstinence than those assigned to identical placebo at the end of the 6-week, double blind, treatment phase. Four-week continuous abstinence will be defined as Timeline Followback Calendar confirmation at study visit of smoking no cigarettes in the past 7 days, and expired air CO\<10ppm for 4 consecutive weeks (the last 4 weeks of the randomized phase)

Secondary Outcome Measures

Name	Time	Method
7-day, Point-prevalence Tobacco Abstinence at the End of the First Week of Exposure to GSK598809/Placebo	Week 3 of the study	The hypothesis is that those assigned to GSK598809 will demonstrate a higher rate of biochemically-verified, 7-day, point-prevalence tobacco abstinence than those assigned to identical placebo at the end of the first week of exposure to GSK598809/placebo.
7-day, Point-prevalence Tobacco Abstinence at the End of 6 Weeks Exposure to GSK598809/Placebo	Week 8 of the study	The hypothesis is that those assigned to GSK598809 will demonstrate a higher rate of biochemically-verified, 7-day, point-prevalence tobacco abstinence than those assigned to identical placebo at the end of 6 weeks exposure to GSK598809/placebo.
Number of Participants With 7-day, Point-prevalence Tobacco Abstinence 2-weeks After Discontinuation of Double Blind Study Medications	Week 10 of the study	The hypothesis is that those assigned to GSK598809 will demonstrate a higher rate of biochemically-verified, 7-day, point-prevalence tobacco abstinence than those assigned to identical placebo two weeks after discontinuation of double blind study medications. 7-day, Point-prevalence tobacco abstinence was defined as not smoking for the 7 consecutive days before this visit after discontinuation of double blind study medications