Phencyclidine (PCP), also known as angel dust among other names, is a drug used for its mind-altering effects. PCP may cause hallucinations, distorted perceptions of sounds, and violent behavior. As a recreational drug, it is typically smoked, but may be taken by mouth, snorted, or injected. It may also be mixed with cannabis or tobacco.
Adverse effects may include seizures, coma, addiction, and an increased risk of suicide. Flashbacks may occur despite stopping usage. Chemically, PCP is a member of the arylcyclohexylamine class, and pharmacologically, it is a dissociative anesthetic. PCP works primarily as an NMDA receptor antagonist.
PCP is most commonly used in the United States. While usage peaked there in the 1970s, between 2005 and 2011 and increase in visits to emergency departments as a result of the drug occurred. As of 2017 in the United States about 1% of people in grade twelve reported using PCP in the prior year while 2.9% of those over the age of 25 reported using it at some point in their life.
PCP was initially made in 1926 and brought to the market as an anesthetic medication in the 1950s. Its use in humans was disallowed in the United States in 1965 due to the high rates of side effects while its use in other animals was disallowed in 1978. Moreover, ketamine was discovered and was better tolerated as an anesthetic. PCP is classified as a Schedule II drug in the United States. A number of derivatives of PCP have been sold for recreational and non-medical use.
Phencyclidine is used for its ability to induce a dissociative state
Behavioral effects can vary by dosage. Low doses produce 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. The drug is often illegally produced under poorly controlled conditions; this means that users may be unaware of the actual dose they are taking.
Psychological effects include severe changes in body image, loss of ego boundaries, paranoia, and depersonalization. Psychosis, agitation and dysphoria, hallucinations, blurred vision, euphoria, and suicidal impulses are also reported, as well as occasional aggressive behavior. Like many other drugs, PCP has been known to alter mood states in an unpredictable fashion, causing some individuals to become detached, and others to become animated. PCP may induce feelings of strength, power, and invulnerability as well as a numbing effect on the mind.
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 limited to individuals with reputations for aggression regardless of drug use. Although uncommon, events of PCP-intoxicated individuals acting in an unpredictable fashion, possibly driven by their delusions or hallucinations, have been publicized. One 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 inflicting property damage and self-mutilation of various types, such as pulling one’s own teeth. These effects were not noted in its medicinal use in the 1950s and 1960s however, and reports of physical violence on PCP 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. Users generally report feeling detached from reality.
Symptoms are summarized by the mnemonic device RED DANES: rage, erythema (redness of the skin), dilated pupils, delusions, amnesia, nystagmus (oscillation of the eyeball when moving laterally), excitation, and skin dryness.
PCP is self-administered and induces ΔFosB expression in the D1-type medium spiny neurons of the nucleus accumbens, and accordingly, excessive PCP use is known to cause addiction. PCP’s rewarding and reinforcing effects are at least partly mediated by blocking the NMDA receptors in the glutamatergic inputs to D1-type medium spiny neurons in the nucleus accumbens. PCP has been shown to produce conditioned place aversion and conditioned place preference in animal studies.
A 2019 review found that the transition rate from a diagnosis of hallucinogen-induced psychosis (which included PCP) to that of schizophrenia was 26%. This was lower than cannabis-induced psychosis (34%) but higher than amphetamine (22%), opioid (12%), alcohol (10%) and sedative (9%) induced psychoses. In comparison, the transition rate for brief, atypical and not otherwise specified psychosis was found to be 36%.