Relapse Prevention Study in Newly Abstinent Smokers

• safety endpoints including vital signs, weight, ECGs, safety laboratory test and adverse events [ Time Frame: weeks 1 through 16 and follow-up phase ] [ Designated as safety issue: Yes ]
• Weekly point prevalence abstinence [ Time Frame: Weeks 6, 8, 10, 12, 14, and 16 ] [ Designated as safety issue: No ]
• drug exposure level [ Time Frame: weeks 6-16 ] [ Designated as safety issue: No ]

The purpose of this study is to determine the effect of GSK598809 as compared to placebo in preventing recently-quit smokers from going back to smoking.

The primary objective of this study is to evaluate the efficacy of GSK598809 compared to placebo for the prevention of relapse to smoking in recently abstinent smokers. Subjects who meet eligibility criteria will enter a 4-week open label treatment period during which they will receive nicotine replacfement therapy (NRT). Subjects who have achieved at least one week of abstinence during the last week of an open label treatment period will be randomized to either GSK598809 or placebo in the double-blind treatment period and followed for another 12 weeks.

• Substance Dependence
• Smoking

• Drug: double blind treatment
  Once subjects complete a 4 week open label period and are eligible to continue, they will start 12 week double blind treaqtment period. For the first week of double blind treatment, subjects will continue to receive nicotine replacement therapy.
• Drug: open label
  Subjects who meet inclusion and exclusion criteria will first enter 4 week open label period of nicotine replacement therapy before they start the 12 week double blind treatment period.

• Placebo Comparator: placebo arm
  Subjects will enter into a 4-week open label period of nicotine replacement therapy and then are randomized into either placebo arm or GSK598809 arm. Subjects in placebo arm will be taking placebo once daily for 12 weeks from week 5 to 16.
  Interventions:

  • Drug: double blind treatment
  • Drug: open label
• Experimental: GSK598809 arm
  Subjects will enter into a 4-week open label period of nicotine replacement therapy and then are randomized into either placebo arm or GSK598809 arm. Subjects in GSK598809 arm will be taking GSK598809 once daily for 12 weeks from weeks 5 to 16.
  Interventions:

  • Drug: double blind treatment
  • Drug: open label

Inclusion Criteria:

• has smoked at least 10 cigarettes a day for at least 2 years
• has had multiple previous attempts to quit smoking and relapsed to smoking.
• generally healthy

Exclusion Criteria:

• cannot be using smokeless tobacco of any type or has tried to quit with medicine.
• does not abuse alcohol or drugs
• certain emotional problems being treated with medications
• pregnant or breast feeding female