False-positive phencyclidine (PCP) on urine drug screen attributed to desvenlafaxine (Pristiq) use.

We report a likely false-positive phencyclidine (PCP) result detected with a urine drug screen (UDS) (Medtox, St Paul, Minnesota, USA) in the setting of therapeutic desvenlafaxine (Pristiq) use. Desvenlafaxine (O-desmethylvenlafaxine) is the active metabolite of venlafaxine (Effexor). Prior reports have confirmed venlafaxine use resulting in a false-positive for PCP on a UDS. However, there has been a paucity of reporting of commercially available desvenlafaxine formulations (Pristiq, Khedezla) resulting in false-positives for PCP on a UDS.