INTRODUCTION
Despite a fall in popularity since the 1970s, phencyclidine (PCP) continues to be used. Approximately 500 exposure cases involving PCP are reported to United States poison centers annually and that number appears to be stable [1]. Early identification and prompt symptomatic treatment are vital to avoid possible sequelae, including rhabdomyolysis and seizures.The basic pharmacology, clinical manifestations, and management of PCP intoxication in adults is reviewed here. The management of PCP poisoning in children, ketamine and other sympathomimetic poisonings, and other issues related to the management of the poisoned patient are discussed separately. (See "Phencyclidine (PCP) intoxication in children and adolescents" and "Ketamine poisoning" and "General approach to drug poisoning in adults".)
PHARMACOLOGY AND CELLULAR TOXICOLOGY
PCP, or 1-(1-phenylcyclohexyl) piperidine hydrochloride, is a synthetic arylcycloalkylamine discovered in 1926 and a dissociative anesthetic. It is synthesized from piperidine and cyclohexanone [2]. It is a weak base with a pKa of 8.6 and is soluble in water and ethanol [3].PCP is a stable white solid with a bitter taste. It is manufactured in many forms for recreational use, including powder, crystal, liquid, and tablets [4]. It has been sprinkled on leaves for ingestion, and there are reports of it being combined with embalming fluid to enable the drug's uniform distribution in cigarettes (often referred to as "wet," "illy," or "fry") [5]. Concentrations of the drug vary in PCP tablets (1 to 6 mg) and PCP-laced marijuana (1 to 10 mg) [6,7].
PCP has a number of analogs that may also be abused, including PHP (rolicyclidine, phenylcyclohexylpyrrolidine), PCE (N-ethyl-1-phenylcyclohexylamine), TCP (1-[1-(2-thienyl) cyclohexyl] piperidine), and PCC (1-piperidinocyclohexane-carbonitrile). PCC is commonly found in street grade PCP. PCC has the potential for increased toxicity due to the release of hydrogen cyanide when smoked [2], although acute cyanide toxicity is unlikely [8]. Another analog 3-Methoxyphencyclidine appears to cause similar effects [9] and has been implicated in several deaths [10-12]. There have been reports of less well-regulated designer drugs related to PCP with similar toxicity profiles including: methoxphenidine (a diarylethylamine) [13], and gacyclidine (a derivative of PCP or TCP) [14].