Current Evidence PCP was developed in the 1950s as a general anesthetic It rapidly fell into disuse because of disturbing emergence syndromes in postoperative patients, but subsequently gained popularity as a drug of abuse, with popularity peaking in the 1970s Ketamine is a PCP analog with approximately one-tenth the potency and a shorter duration of action that is used for several therapeutic indications, but also may be a drug of abuse Ketamine is discussed in detail in Chapter 129 Procedural Sedation Another drug with related structure, but milder effects, is dextromethorphan, which is popular with adolescents because of its ready availability as a legal, OTC cough suppressant PCP is easily synthesized and is often sold on the streets misrepresented as LSD, mescaline, or marijuana It is well absorbed across all mucous membranes and is most popularly used by inhalation (often mixed into cigarettes or marijuana joints), but it can be ingested, injected, or insufflated Chemically, PCP is an arylcyclohexylamine More recently, novel PCP analogs (including methoxetamine and 3- and 4-methoxyphencyclidine) have been identified as emerging drugs of abuse This group of drugs has a range of CNS actions that range from hallucinations with smaller doses, to stimulation with moderate doses (occasionally associated with seizures), to profound CNS depression with respiratory arrest with large doses There is great variability in the metabolism of PCP In general, 0.1 mcg/mL is considered a toxic serum level One cigarette may contain to 100 mg A dose of to 10 mg may produce stupor and coma; with doses exceeding 10 mg, respiratory depression and convulsions occur A fatal dose is in the range of mg/kg Because PCP has a long elimination half-life (18 hours), clinical symptoms may last for more than 12 hours; also, patients may have recurrent symptoms when the drug undergoes enterohepatic recirculation