General prevalence. Tranquillizers and sedatives include benzodiazepines such as alprazolam (e.g. Xanax), clonazepam (e.g. Rivotril), diazepam (e.g. Valium), temazepam and flunitrazepam (e.g. Rohypnol); barbiturates such as allobarbital, barbital, phenobarbital, pentobarbital, and secbutabarbital; gamma-hydroxybutyric acid (GHB); and other sedative hypnotics such as meprobamate, methaqualone (Mandrax) and zolpidem.
Source: UNODC