Phencyclidine (PCP or “angel dust”) was initially developed as an anesthetic agent, although it has been mostly used as a recreational drug. PCP works as an NMDA receptor antogonist, producing hallucinogenic and neurotoxic effects. PCP works primarily as an NMDA receptor antagonist, which blocks the activity of the NMDA receptor and, like most antiglutamatergic hallucinogens, is significantly more dangerous than other categories of hallucinogens. The use of PCP has been associated with Olney’s lesions in the brain, although these results have been shown in studies with rats and it is unclear if these occur in humans.