Alprazolam is a benzodiazepine with anxiolytic and sedative actions. 4-Hydroxyalprazolam is a major metabolite of alprazolam, produced by the actions of cytochrome P450 (CYP) isoforms CYP3A4 and CYP3A5. It may be detected in serum or, in a glucuronidated form, in urine. Alternatively, 4-hydroxyalprazolam can be further metabolized to benzophenone.