This is a Phase 2a safety/tolerably study to determine if there are clinically significant interactions between oral vigabatrin (gamma vinyl-gamma-amino butyric acid; VGB) concurrent with intravenous (IV) cocaine infusions.

STUDY DESIGN: This is a randomized, double-blind, placebo-controlled, parallel group study of the effects of VGB compared to placebo control on the physiological and subjective effects of IV infusions of cocaine (cocaine experienced volunteers).

Subjects will be randomized within each clinical site to one of four groups (placebo control or one of three doses of VGB twice daily).During VGB steady state dosing, subjects will receive double-blind infusions of saline and cocaine. Subjects will be asked to return for follow-up approximately 7 and 14 days after the day of clinic discharge.

STUDY DURATION: The maximum duration is 56 days, including 14 inpatient days of assessments and investigational products administration, and two follow-up visits after clinic discharge.

SAMPLE SIZE: Twenty-four subjects will be randomized to one of three doses of vigabatrin or placebo.

POPULATION: Volunteer, cocaine-experienced, non-treatment seeking cocaine users, 18 to 45 years of age.

• Drug: Vigabatrin
• Drug: Matching placebo

Inclusion Criteria:

• Be between 18 and 45 years of age, inclusive
• Currently be a non-treatment seeking cocaine user as confirmed by a positive urine test for cocaine
• Able to provide written informed consent
• A negative pregnancy test within 72 hours prior to receiving the first infusion of cocaine

Exclusion Criteria:

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