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PCP

Category: Medicines

Type

Involuntary and voluntary

Introduction and description

 

Phencyclidine is commonly known as PCP and by nicknames like ‘angel dust’.

It is yet another pharmaceutical that has hovered between illegal then legal and back to illegal again.  It is a 'dissociative' drug, developed originally for use as an anaesthetic but found to be too dangerous to use medically. 

PCP was first synthesized in 1926, and later tested after World War II as a surgical anaesthetic. Patients experienced not just hallucinations but mania and delirium, paranoia and other psychoses with schizophrenic like symptoms and it was shelved until the 1950s.

In 1953, it was patented by Parke-Davis and named Sernyl  - from serenity!

It was only used in humans for a few years  - again because of the side-effects.

 

In 1967, it was given the trade name Sernylan and marketed as a veterinary anesthetic.  There are no records as to what it did to animals that we could find.

It was discovered by drug users in the mid 1960s and PCP powder from “clandestine sources” became part of the  "street drugs" illegally used by narcotic addicts, at one time displacing heroin. It was sold in dilute powder form alone, or admixed with LSD, amphetamine, cocaine, tetrahydrocannabinol (THC), mescaline and other drugs, producing highly toxic mixtures. Users of  these "street drugs" have experienced violent mental disturbances. PCP is properly classed as a "dangerous drug".

Wikipedia

there have been … 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 inflicting property damage and self-mutilation of various types, such as pulling one's own teeth.

and more............

 Receptor activity

 

 

PCP works primarily as an NMDA receptor antagonist, which blocks the activity of the NMDA receptor, leading to amnesia and memory loss.  But it also acts via other receptors. 

It is a dopamine agonist.  A dopamine agonist is a compound that activates dopamine receptors in the absence of dopamine.  To quote  “The most troubling clinical effects are most likely produced by the action of phencyclidine on the D2 receptor. This has been suggested to account for most of the psychotic features”.    Effects of too high a dose can include include:

  • Hallucinations – the halllucinations experienced via PCP are can be bizarre,  frightening and ‘self challenging’
  • Causing or worsening psychosis
  • Insomnia
  • Dizziness, drowsiness, lightheadedness, fainting and disorientation - You may get slurred speech, as well as ataxia where you will experience a  gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying disfunction of the parts of the nervous system that coordinate movement
  • Twitching, twisting, or other unusual body movements
  • Pathological addiction (gambling, shopping, internet pornography, hyper-sexuality)
 

 It also has anticholinergic properties through blockade of ion channels in acetylcholine receptors.  This makes PCP a deleriant as well as a dissociative.  Antagonistic action like this can result in:

  • Paralysis - At higher doses you will become catatonic
  • Loss of  memory – amnesia partial or total
  • Raging thirst [dry mouth]
  • Nausea, etc
  • Tachycardia - hypertension and arrhythmias, vasoconstriction - constricted veins and arteries causing high blood pressure
  • Eye problems – you may be unable to focus your eyes, there may be blurred vision and dilated pupils

 At certain doses  there are many stimulant effects, which leads one to suspect that other receptors may be at work as yet undiscovered and there can be aggressive behaviour, as well as quite self destructive behaviour.

Although the primary psychoactive effects of the drug lasts for a few hours, the total elimination rate from the body typically extends eight days or longer.

 PCP is relatively more toxic to the aged. Mis-synthesis of PCP produces by-products that are very toxic, causing abdominal cramps, bloody emesis, coma and respiratory death (Lampe, 1971).

Seizures, coma and death have occurred [SED-11, 86].

 

Method of use

As a 'recreationa'l drug, PCP may be ingested, smoked, or snorted.  Smoking appears to have been the favourite in the USA.

When smoked PCP is broken down by heat into 1-phenyl-1-cyclohexene (PC) and piperidine.  Piperidine is present in numerous natural alkaloids including the fire ant toxin solenopsin, the nicotine analog anabasine of the Tree Tobacco (Nicotiana glauca), lobeline of the indian tobacco, and the toxic alkaloid coniine from poison hemlock, which was used to put Socrates to death. 

Other PCP like products

There are well over 30 analogues of PCP or products that have very PCP like effects, the following are the main ones:

  • Dexoxadrol (Dioxadrol) produced similar effects to PCP in animals. It, along with another related drug etoxadrol, were developed for use in humans, but development was discontinued after patients reported “side effects such as nightmares and hallucinations”.
  • Eticyclidine (PCE, CI-400) is an anaesthetic with hallucinogenic effects. It is similar in effects to phencyclidine  - PCP  - but is slightly more potent. PCE was developed in the 1970s but research into PCE was not continued after the development of ketamine, which has ‘ more favourable properties’ PCE is more potent than PCP and has similar effects, but its unpleasant taste and tendency to cause nausea made it less accepted by drug users. Due to its similarity in effects to PCP, PCE was placed into the Schedule 1 list of illegal drugs in the 1970s, and is now little known
  • Gacyclidine (GK-11)  - is closely related to phencyclidine (PCP), and specifically, is a derivative of tenocyclidine (TCP).  I could find no observations of use
  • NEFA - is a structural analog of phencyclidine PCP
  • PCDE - Dieticyclidine (PCDE), or diethylphenylcyclohexylamine, is a  research chemical related to phencyclidine (PCP) and eticyclidine (PCE). It has low potency.  I could find no [genuine] examples of its use.
  • Rolicyclidine (PCPy) is similar in effect to phencyclidine but is slightly less potent and has less stimulant effects instead producing a sedative effect, but with additional PCP-like effects. Due to its similarity in effects to PCP, PCPy was placed into the Schedule I list of illegal drugs in the 1970s, although it has never been widely abused and is now little known.  I could find no observations of use
  • Selfotel (CGS-19755) was originally researched for the treatment of stroke but subsequent animal and human studies showed ‘phencyclidine-like effects’ and so clinical development was ultimately discontinued. 
  • Tenocyclidine  (TCP)  - is similar in effects to phencyclidine (PCP) but is considerably more potent. TCP has slightly different binding properties to PCP, with more affinity for the NMDA receptors.  Due to its similarity in effects to PCP, however, TCP was placed into the Schedule I list of illegal drugs in the 1970s, although it was only briefly used in the 1970s and 1980s and is now little known.   I could find no observations of use
  •  
    2-MDP (U-23807A) produces similar effects to PCP in animals
  • 8a-Phenyldecahydroquinoline (8A-PDHQ) is a structural analogue of Phencyclidine with slightly lower binding affinity than the parent compound.    I could find no observations of use

 

Ther Adv Psychopharmacol. 2015 Apr;5(2):97-132. -Legal highs: staying on top of the flood of novel psychoactive substances -  Baumeister D, Tojo LM, Tracy DK  - King's College, London, UK

There has been growing clinical, public, and media awareness and concern about the availability and potential harmfulness of so-called 'legal highs', which are more appropriately called new  psychoactive substances (NPS).

A cat-and-mouse process has emerged wherein unknown chemists and laboratories are producing new, and as yet nonproscribed, compounds for human consumption; and as soon as they are banned, which they inevitably are, slightly modified analogues are produced to circumvent new laws.

This rapidly changing environment produced 81 new substances in 2013 alone, and has led to confusion for clinicians, psychopharmacologists, and the public at large.

Our difficulties in keeping up with the process has had a two-fold negative effect: the danger of ignoring what is confusing; and the problem that some of the newer synthesized compounds appear ever more potent.

This review aims to circumscribe a quick moving and growing field, and to categorize NPS into five major groups based upon their 'parent' compounds:

  • stimulants similar to cocaine, amphetamines and ecstasy;
  • cannabinoids;
  • benzodiazepine based drugs;
  • dissociatives similar to ketamine and phencyclidine (PCP);
  • and those modelled after classic hallucinogens such as LSD and psilocybin.

....Clinicians might encounter NPS in various ways: anecdotal reportage; acute intoxication; as part of a substance misuse profile; and as a precipitant or perpetuating factor for longer-term physical and psychological ill health.

Current data are overall limited, and much of our knowledge and treatment strategies are based upon those of the 'parent' compound. There is a critical need for more research in this field, and for professionals to make themselves more aware of this growing issue and how it might affect those we see clinically and try to help: .....PMID: 26240749

 

References and further reading

A man with drug-induced psychosis attempts to swallow his cellular phone. -Levy Z, Jesus J, Osborne A, Matthews P. Intern Emerg Med. 2013 Sep;8(6):541-2. doi: 10.1007/s11739-013-0950-x. Epub 2013 May 5.  PMID: 23645510

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