Effects of ABT-089 on Smoking Abstinence Symptoms and Reward

This is a single-site, phase IIa, double-blind, within-subject, cross-over, human laboratory study. Subjects will be healthy, treatment-seeking female and male adult smokers, ages 18 to 65 years old. Subjects deemed eligible for participation after an Intake Visit (\~Day -7) will complete baseline assessments and receive period 1 medication (ABT-089 or placebo) at the Baseline Visit (Day 0). Subjects will take 40mg of ABT-089 or placebo, based on random assignment, every day for two identical 10-day study treatment periods. Subjects will begin period 1 study medication on Day 1. On Days 3 and 5, subjects will complete in-clinic medication run-up and monitoring assessments. On Day 5, subjects will begin a \~24-hour period of mandatory abstinence from smoking. Day 6 is conducted in two parts. Part 1 will consist of confirmation of smoking abstinence, testing for abstinence-induced cognitive deficits and the collection of subjective assessments. Part 2 will begin with a programmed smoking lapse, after which the subjective rewarding value of the programmed lapse cigarette will be assessed. Before leaving the clinic on Day 6, subjects will receive brief cessation counseling and be instructed to try to remain abstinent from 10pm that evening until after the final Observation Visit on Day 10. During the \~4-day monitored abstinence/observation phase, subjects will complete in-clinic observation visits (subjective assessments, medication adherence, etc.) on Days 7, 8, and 10. After a \~3-week medication washout period and Period 2 Medication Pick-up Visit on \~Day 31, subjects will begin study medication (either ABT-089 or placebo; but will always be the opposite of the assigned study medication in period 1) and participate in period 2 of the study following the same procedures as period 1.