- The subject has a positive pre-study drug/alcohol screen. A minimum list of drugs that will be screened for include cannabinoids, amphetamines, barbiturates, cocaine and opiates. The detection of drugs (e.g. benzodiazepines, opiates) taken for a legitimate medical purpose would not necessarily be an exclusion to study participation. The detection of alcohol would not be an exclusion at screening but would need to be negative pre-dose and during the study.