Phencyclidine (PCP) and Ketamine
Phencyclidine, or PCP [1-(1-phenylcyclohexyl)-piperidine], is a dissociative anesthetic agent with properties similar to those of ketamine. It previously was marketed for veterinary use and became popular as an inexpensive street drug in the late 1960s. PCP is most commonly smoked but may also be snorted, ingested, or injected. It is frequently substituted for or added to illicit psychoactive drugs such as THC (tetrahydrocannabinol, or marijuana), mescaline, and LSD. PCP is known by a variety of street names, including “peace pill,” “angel dust,” “hog,” “goon,” “animal tranquilizer,” and “krystal.” “Sherms” is slang for Sherman cigarettes laced with PCP, and a “KJ” is a marijuana cigarette laced with PCP. Various chemical analogs of PCP have been synthesized, including PCC (1-piperidonocyclohexanecarbinol), PCE (1-phenyl-cyclohexylethylamine), PHP (phenylcyclohexylpyrrolidine), and TCP [1(1-cyclohexyl)piperidine].
Ketamine [2-(2-chlorophenyl)-2-(methylamino)cyclohexanone] shares many pharmacologic and clinical characteristics with PCP. Although currently used as an anesthetic agent and for procedural sedation, ketamine is a popular drug of abuse owing to its dissociative, analgesic, and hallucinogenic properties. It was first used as a street drug in the 1970s and gained popularity in the club scene of the 1990s. Street names for ketamine include “K,” “special K,” “vitamin K,” “jet,” “special LA coke,” and “super C.” A severe ketamine intoxication is referred to as “falling into the K-hole.”
Mechanism of toxicity
PCP and ketamine are dissociative anesthetics that produce generalized loss of pain perception with little or no depression of airway reflexes or ventilation. Psychotropic effects are primarily mediated through N-methyl-d-aspartate (NMDA) receptor antagonism. They also inhibit reuptake of dopamine, norepinephrine, and serotonin and block potassium conductance in the brain. PCP stimulates the sigma-opioid receptor, and ketamine stimulates the mu-, delta-, sigma-, and kappa-opioid receptors. PCP also binds to a site within the L-type calcium channel, thus attenuating the influx of calcium when excitatory neurotransmitters bind to this receptor.
Pharmacokinetics
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