Phencyclidine or phenylcyclohexyl piperidine (PCP), also known in its use as a street drug as angel dust among other names, is a dissociative anesthetic mainly used recreationally for its significant 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.
Dissociatives, colloquially dissos, are a subclass of hallucinogens which distort perception of sight and sound and produce feelings of detachment – dissociation – from the environment and/or self. Although many kinds of drugs are capable of such action, dissociatives are unique in that they do so in such a way that they produce hallucinogenic effects, which may include dissociation, a general decrease in sensory experience, hallucinations, dream-like states or anesthesia. Despite most dissociatives' main mechanism of action being tied to NMDA receptor antagonism, some of these substances, which are nonselective in action and affect the dopamine and/or opioid systems, may be capable of inducing more direct and repeatable euphoria or symptoms which are more akin to the effects of typical "hard drugs" or common drugs of abuse. This is likely why dissociatives are considered to be addictive with a fair to moderate potential for abuse, unlike psychedelics. Despite some dissociatives, such as phencyclidine (PCP) possessing stimulating properties, most dissociatives seem to have a general depressant effect and can produce sedation, respiratory depression, nausea, disorientation, analgesia, anesthesia, ataxia, cognitive and memory impairment as well as amnesia.
Methcathinone is a monoamine alkaloid and psychoactive stimulant, a substituted cathinone. It is used as a recreational drug due to its potent stimulant and euphoric effects and is considered to be addictive, with both physical and psychological withdrawal occurring if its use is discontinued after prolonged or high-dosage administration. It is usually snorted, but can be smoked, injected, or taken orally.
Dizocilpine (INN), also known as MK-801, is a pore blocker of the NMDA receptor, a glutamate receptor, discovered by a team at Merck in 1982. Glutamate is the brain's primary excitatory neurotransmitter. The channel is normally blocked with a magnesium ion and requires depolarization of the neuron to remove the magnesium and allow the glutamate to open the channel, causing an influx of calcium, which then leads to subsequent depolarization. Dizocilpine binds inside the ion channel of the receptor at several of PCP's binding sites thus preventing the flow of ions, including calcium (Ca2+), through the channel. Dizocilpine blocks NMDA receptors in a use- and voltage-dependent manner, since the channel must open for the drug to bind inside it. The drug acts as a potent anti-convulsant and probably has dissociative anesthetic properties, but it is not used clinically for this purpose because of the discovery of brain lesions, called Olney's lesions (see below), in laboratory rats. Dizocilpine is also associated with a number of negative side effects, including cognitive disruption and psychotic-spectrum reactions. It inhibits the induction of long term potentiation and has been found to impair the acquisition of difficult, but not easy, learning tasks in rats and primates. Because of these effects of dizocilpine, the NMDA receptor pore blocker ketamine is used instead as a dissociative anesthetic in human medical procedures. While ketamine may also trigger temporary psychosis in certain individuals, its short half-life and lower potency make it a much safer clinical option. However, dizocilpine is the most frequently used uncompetitive NMDA receptor antagonist in animal models to mimic psychosis for experimental purposes.
5-MeO-MiPT is a psychedelic and hallucinogenic drug, used by some as an entheogen. It has structural and pharmacodynamic properties similar to the drugs 5-MeO-DiPT, DiPT, and MiPT. It is commonly used as a "substitute" for 5-MeO-DiPT because of the very similar structure and effects.
NMDA receptor antagonists are a class of drugs that work to antagonize, or inhibit the action of, the N-Methyl-D-aspartate receptor (NMDAR). They are commonly used as anesthetics for human and non-human animals; the state of anesthesia they induce is referred to as dissociative anesthesia.
Rolicyclidine (PCPy) is a dissociative anesthetic that is similar in effects to phencyclidine, but is slightly less potent and has fewer stimulant effects. It instead produces a sedative effect described as being somewhat similar to a barbiturate, but with additional PCP-like dissociative, anaesthetic and hallucinogenic 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.
Tenocyclidine (TCP) is a dissociative anesthetic with psychostimulant effects. It was discovered by a team at Parke-Davis in the late 1950s. It 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, but less affinity for the sigma receptors. Because of its high affinity for the PCP site of the NMDA receptor complex, the 3H radiolabelled form of TCP is widely used in research into NMDA receptors.
Etoxadrol (CL-1848C) is a dissociative anaesthetic drug that has been found to be an NMDA antagonist and produce similar effects to PCP in animals. Etoxadrol, along with another related drug dexoxadrol, were developed as analgesics for use in humans, but development was discontinued in the late 1970s after patients reported side effects such as nightmares and hallucinations.
Benocyclidine, also known as benzothiophenylcyclohexylpiperidine (BTCP), is a psychoactive recreational drug of the arylcyclohexylamine class which is related to phencyclidine (PCP). It was first described in a patent application naming Marc Caron and colleagues at Duke University in 1997.
Arylcyclohexylamines, also known as arylcyclohexamines or arylcyclohexanamines, are a chemical class of pharmaceutical, designer, and experimental drugs.
3-Methoxyphencyclidine (3-MeO-PCP) is a dissociative hallucinogen of the arylcyclohexylamine class related to phencyclidine (PCP) which has been sold online as a designer drug. It acts mainly as an NMDA receptor antagonist, though it has also been found to interact with the sigma σ1 receptor and the serotonin transporter. The drug does not possess any opioid activity nor does it act as a dopamine reuptake inhibitor.
4-Methoxyphencyclidine is a dissociative anesthetic drug that has been sold online as a research chemical. The synthesis of 4-MeO-PCP was first reported in 1965 by the Parke-Davis medicinal chemist Victor Maddox. A 1999 review published by a chemist using the pseudonym John Q. Beagle suggested the potency of 4-MeO-PCP in man was reduced relative to PCP, two years later Beagle published a detailed description of the synthesis and qualitative effects of 4-MeO-PCP, which he said possessed 70% the potency of PCP. 4-MeO-PCP was the first arylcyclohexylamine research chemical to be sold online, it was introduced in late 2008 by a company trading under the name CBAY and was followed by several related compounds such as 3-MeO-PCP and methoxetamine. 4-MeO-PCP has lower affinity for the NMDA receptor than PCP, but higher affinity than ketamine, it is orally active in a dosage range similar to ketamine, with some users requiring doses in excess of 100 mg for desired effects. Users have reported substantial differences in active dose, these discrepancies can be partially explained by the presence of unreacted PCC and other impurities in samples sold on the grey market. 4-MeO-PCP has Ki values of 404 nM for the NMDA receptor, 713 nM for the norepinephrine transporter, 844 nM for the serotonin transporter, 296 nM for the σ1 receptor and 143 nM for the σ2 receptor.
PCPr is an arylcyclohexylamine dissociative anesthetic drug with hallucinogenic and stimulant effects. It is around the same potency as phencyclidine, although slightly less potent than the ethyl homologue eticyclidine, and has reportedly been sold as a designer drug in Germany and other European countries since the late 1990s.
Methoxetamine, abbreviated as MXE, is a dissociative hallucinogen that has been sold as a designer drug. It differs from many dissociatives such as ketamine and phencyclidine (PCP) that were developed as pharmaceutical drugs for use as general anesthetics in that it was designed specifically to increase the antidepressant effects of ketamine.
3-Methoxyeticyclidine (3-MeO-PCE), also known as methoxieticyclidine, is a dissociative anesthetic that is qualitatively similar to PCE and PCP and has been sold online as a designer drug.
3-MeO-PCMo is a dissociative anesthetic drug which is similar in structure to phencyclidine and been sold online as a designer drug. The inhibitory effect of 3-MeO-PCMo on the reduction in the density of the drebrin clusters by NMDAR stimulation with glutamic acid is lower than that of PCP or 3-MeO-PCP, with half maximal inhibitory concentration (IC50) values of 26.67 μM (3-MeO-PCMo), 2.02 μM (PCP) and 1.51 μM (3-MeO-PCP).
3-Hydroxyphencyclidine (3-HO-PCP) is a dissociative of the arylcyclohexylamine class related to phencyclidine (PCP) that has been sold online as a designer drug.
2-Oxo-PCE is a dissociative anesthetic of the arylcyclohexylamine class that is closely related to deschloroketamine and eticyclidine, and has been sold online as a designer drug.
3-Chloro-PCP (3'-Cl-PCP) is a recreational designer drug from the arylcyclohexylamine family, with dissociative effects. It has comparable potency to phencyclidine but with a slightly different effects profile, being somewhat more potent as an NMDA antagonist but around the same potency as a dopamine reuptake inhibitor. It was first identified in Slovenia in December 2020, and was made illegal in Hungary in April 2021.
