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"P.C.P." redirects here. For the Manic Street Preachers song, see Faster/P.C.P..
PCP is well known for its primary action on ionotropicglutamate receptors, such as the NMDA receptor in rats and in rat brain homogenate. As such, PCP is an NMDA receptor antagonist. NMDA receptors mediate excitation, however, studies have shown that PCP unexpectedly produces substantial cortical activation in humans and rodents.
Research also indicates that PCP inhibits nicotinicacetylcholine (nACh) receptors. Analogues of PCP exhibit varying potency at nACh receptors and NMDA receptors. In some brain regions, these effects are believed to act synergistically by inhibiting excitatory activity.
PCP, like ketamine, also acts as a D2 receptorpartial agonist in rat brain homogenate. This activity may be associated with some of the more 8 other psychotic features of PCP intoxication, which is evidenced by the successful use of D2 receptor antagonists (such as haloperidol) in the treatment of PCP psychosis.
Studies on rats indicate that PCP indirectly interacts with endorphin and enkephalin receptors to produce analgesia. 
More than 30 different analogues of PCP were reported as being used on the street during the 1970s and 1980s, mainly in the USA. The best known of these are rolicyclidine (PCPy or 1-(1-phenylcyclohexyl)pyrrolidine); eticyclidine (PCE or N-ethyl-1-phenylcyclohexylamine); and tenocyclidine (TCP or 1-(1-(2-thienyl)cyclohexyl)piperidine). These compounds were never widely used and did not seem to be as well accepted by users as PCP itself, however they were all added onto Schedule I of the Controlled Substance Act because of their putative similar effects.
The generalized structural motif required for PCP-like activity is derived from structure-activity relationship studies of PCP analogues, and summarized below. All of these analogues would have somewhat similar effects to PCP itself, although, with a range of potencies and varying mixtures of anesthetic, dissociative and stimulant effects depending on the particular substituents used. In some countries such as the USA, Australia, and New Zealand, all of these compounds would be considered controlled substance analogues of PCP, and are hence illegal drugs, even though many of them have never been made or tested.[clarification needed]
Some studies found that, like other NMDA receptor antagonists, phencyclidine can cause a kind of brain damage called Olney's lesions in rats. Studies conducted on rats showed that high doses of the NMDA receptor antagonist dizocilpine caused reversible vacuoles to form in certain regions of the rats' brains. All studies of Olney's lesions have only been performed on non-human animals and may not apply to humans. One unpublished study by Frank Sharp reportedly showed no damage by the NDMA antagonist, ketamine, a similar drug, far beyond recreational doses,  but due to the study never having been published, its validity is highly controversial.
Phencyclidine has also been shown to cause schizophrenia-like changes in N-acetylaspartate and N-acetylaspartylglutamate in the rat brain, which are detectable both in living rats and upon necropsy examination of brain tissue. It also induces symptoms in humans that mimic schizophrenia.
PCP began to emerge as a recreational drug in major cities in the United States in 1967. In 1978, People magazine and Mike Wallace of 60 Minutes called PCP the country's "number one" drug problem. Although recreational use of the drug had always been relatively low, it began declining significantly in the 1980s. In surveys, the number of high school students admitting to trying PCP at least once fell from 13% in 1979 to less than 3% in 1990.
PCP is a Schedule II substance in the United States, a Schedule I drug by the Controlled Drugs and Substances act in Canada, a List I drug of the Opium Law in the Netherlands and a Class A substance in the United Kingdom.
The term "embalming fluid" is often used to refer to the liquid PCP in which a cigarette is dipped, to be ingested through smoking, commonly known as "boat" or "water." The name most likely originated from the somatic "numbing" effect and feelings of dissociation induced by PCP, and has led to the widespread and mistaken belief that the liquid is made up of or contains real embalming fluid. Occasionally, however, some users and dealers could have, believing this myth, used real embalming fluid mixed with, or in place of, PCP. Smoking PCP is known as "getting wet", and a cigarette or joint which has been dipped in PCP may be referred to on the street as a "fry stick," "sherm," "leak," "amp," "lovely," "KJ (an abbreviation for 'Killer Joint')," "toe tag", "dipper", "happy stick," or "wet stick." "Getting wet" may have once been a popular method of using PCP, especially in the western United States where it may have been sold for about $10 to $25 per cigarette.
Behavioral effects can vary by dosage. Low doses produce a numbness in the extremities and intoxication, characterized by staggering, unsteady gait, slurred speech, bloodshot eyes, and loss of balance. Moderate doses (5–10 mg intranasal, or 0.01–0.02 mg/kg intramuscular or intravenous) will produce analgesia and anesthesia. High doses may lead to convulsions. Users frequently do not know how much of the drug they are taking due to the tendency of the drug to be made illegally in uncontrolled conditions.
Studies by the Drug Abuse Warning Network in the 1970s show that media reports of PCP-induced violence are greatly exaggerated and that incidents of violence are unusual and often (but not always) limited to individuals with reputations for aggression regardless of drug use. This said, there have been a few, very-televised events of PCP-intoxicated individuals acting in an unpredictable fashion, possibly driven by their delusions or hallucinations. One famous example is the case of Big Lurch, a former rapper with a history of violent crime, who was convicted of murdering and cannibalizing his roommate while under the influence of PCP. Other commonly cited types of incidents include self-mutilation of various types, breaking handcuffs, inflicting remarkable property damage, and pulling one's own teeth.[full citation needed] These effects were not noted in its medicinal use in the 50s and 60s, however, and reports of physical violence on phencyclidine have often been shown to be unfounded.
Recreational doses of the drug also occasionally appear to induce a psychotic state that resembles a schizophrenic episode, sometimes lasting for months at a time. Users generally report they feel detached from reality.
Symptoms are summarized by the mnemonic device RED DANES: rage, erythema (redness of skin), dilated pupils, delusions, amnesia, nystagmus (oscillation of the eyeball when moving laterally), excitation, and skin dryness.
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