Phencyclidine, or PCP [1-(1-phenylcyclohexyl)-piperidine], is an arylcyclohexylamine dissociative anesthetic agent with stimulant properties. It was previously 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) and rarely, mescaline or LSD. PCP is known by a variety of street names, including "peace pill," "angel dust," "hog," "goon," and "animal tranquilizer." "Sherms" is slang for Sherman cigarettes laced with PCP, and a "KJ" is a marijuana cigarette laced with PCP. Various structural analogs of PCP have been synthesized, including PCC (1-piperidonocyclohexanecarbinol), PCE (eticyclidine; 1-phenyl-cyclohexylethylamine), PHP (rolicyclidine; phenylcyclohexylpyrrolidine), and TCP (tenocyclidine; 1-(1-cyclohexyl) piperidine).
Ketamine [2-(2-chlorophenyl)-2-(methylamino)cyclohexanone] shares many structural, 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." Methoxetamine [MXE; 2-(3-methoxyphenyl)-2-(amino)cyclohexanone] is a structural analog of ketamine that may be associated with worse side effects of cerebellar ataxia and mood disturbances.
MECHANISM OF TOXICITY
PCP, ketamine, and their analogs 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.
PCP is absorbed rapidly by inhalation or ingestion. It is highly lipophilic and has a large volume of distribution (Vd) of about 6 L/kg. The duration of clinical effects after an overdose is highly variable and ranges from 11 to 14 hours in one report to 1–4 days in another. PCP is eliminated mainly by hepatic metabolism, although renal and gastric excretion accounts for a small fraction and is pH-dependent (see also Table II–66).
Ketamine is well absorbed after snorting and injection and poorly with oral and rectal ingestion. Effect onset occurs 30 seconds to 30 minutes after use and lasts up to 3 hours, depending on the route of administration. It is metabolized by the liver. The kidney is an important route of elimination for norketamine, the active metabolite of ketamine. The volume of distribution of ketamine is approximately 2–4 L/kg.
Methoxetamine effects occur 30–90 minutes ...