- Has a positive screen for drugs with a high potential for abuse such as cocaine, amphetamines, methylenedioxymethamphetamine (MDMA), barbiturates, benzodiazepines (exceptions apply), or opiates/opioids (apart from methadone as assigned maintenance therapy) on Day 1 that cannot be explained by concomitant medications, unless at the discretion of the principal investigator and the sponsor. Must have a negative Urine Drug Screen prior to randomization, with the exception of tetrahydrocannabinol (THC) and prescription benzodiazepines.