Eligibility Criteria:
Inclusion Criteria:
* Current recreational polydrug users with experience with at least 2 drug classes of abuse.
* At least 10 lifetime uses of stimulants drugs (eg, amphetamine, cocaine, methamphetamine) and 10 lifetime occasions of recreational use of psychedelic drugs (eg, cannabis, ketamine, dextromethorphan, PCP, MDMA \[ecstasy\], LSD, mesacline, or psilocybin).
* Recreational use of other classes of drugs is permitted, including opioids (eg, codeine, morphine, or heroin), minor tranquilizers, or sedatives (eg, benzodiazepines or barbiturates).
* Male or female volunteers aged 18 to 55, inclusive with a body mass index (BMI) within the range of 19.0 to 33.0 kg/m2, inclusive, and a minimum weight of 50.0 kg at screening.
* Must pass qualification phase eligibility criteria.
Exclusion Criteria:
* Self-reported history of drug or alcohol dependence (except caffeine) in the past 12 months, including subjects who have ever been in a drug rehabilitation program (other than treatment for smoking cessation).
* Unwillingness or inability to abstain from recreational drug use for the duration of the study from screening until follow-up.
* Positive for hepatitis B, hepatitis C, or human immunodeficiency virus (HIV) at screening.
* Any significant unstable hepatic, renal, pulmonary, cardiovascular, ophthalmologic, neurologic, or any other medical conditions that might confound the study or put the volunteer at greater risk during study participation.
* Currently smoking more than 20 cigarettes (or 2 cigars) per day, and/or unwillingness to abstain from smoking for durations of at least 12 hours.
* Use of tobacco cessation product within 1 month (eg, nicotine substitution products, bupropion, etc).