HallucinogenHallucinogens are a large and diverse class of psychoactive drugs that can produce altered states of consciousness characterized by major alterations in thought, mood, and perception as well as other changes. Most hallucinogens can be categorized as either being psychedelics, dissociatives, or deliriants. The word hallucinogen is derived from the word hallucination. The term hallucinate dates back to around 1595–1605, and is derived from the Latin hallūcinātus, the past participle of (h)allūcināri, meaning "to wander in the mind.
OpioidOpioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, reversing opioid overdose, and suppressing cough. Extremely potent opioids such as carfentanil are approved only for veterinary use. Opioids are also frequently used non-medically for their euphoric effects or to prevent withdrawal.
DextromethorphanDextromethorphan (DXM) is a cough suppressant in over-the-counter cold and cough medicines. It affects NMDA, glutamate-1, and sigma-1 receptors in the brain, all of which have been implicated in the pathophysiology of depression. In 2022, the FDA approved a formulation of it combined with bupropion named Auvelity to serve as a rapid acting antidepressant in patients with major depressive disorder. It is sold in syrup, instant release tablet, extended release tablet, spray, and lozenge forms.
Psychoactive drugA psychoactive drug, psychopharmaceutical, psychoactive agent, or psychotropic drug is a chemical substance that changes the function of the nervous system and results in alterations of perception, mood, cognition, and behavior. These substances may be used medically, recreationally, for spiritual reasons (for example, by altering one's consciousness, as with entheogens for ritual, spiritual, or shamanic purposes), or for research. Some categories of psychoactive drugs may be prescribed by physicians and other healthcare practitioners because of their therapeutic value.
NMDA receptor antagonistNMDA 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 animals and humans; the state of anesthesia they induce is referred to as dissociative anesthesia. Several synthetic opioids function additionally as NMDAR-antagonists, such as pethidine, levorphanol, methadone, dextropropoxyphene, tramadol and ketobemidone.
PhencyclidinePhencyclidine or phenylcyclohexyl piperidine (PCP), also known 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. Adverse effects may include seizures, coma, addiction, and an increased risk of suicide.
KetamineKetamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a treatment for depression, a pain management tool, and as a recreational drug. Ketamine is a novel compound that was derived from phencyclidine in 1962, in pursuit of a safer anesthetic with fewer hallucinogenic effects. At anesthetic doses, ketamine induces a state of "dissociative anesthesia", a trance-like state providing pain relief, sedation, and amnesia.
Dissociation (psychology)Dissociation is a concept that has been developed over time and which concerns a wide array of experiences, ranging from a mild emotional detachment from the immediate surroundings, to a more severe disconnection from physical and emotional experiences. The major characteristic of all dissociative phenomena involves a detachment from reality, rather than a loss of reality as in psychosis. The phenomena are diagnosable under the DSM-5 as a group of disorders as well as a symptom of other disorders through various diagnostic tools.
NMDA receptorThe N-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA and kainate receptors. Depending on its subunit composition, its ligands are glutamate and glycine (or D-serine). However, the binding of the ligands is typically not sufficient to open the channel as it may be blocked by Mg2+ ions which are only removed when the neuron is sufficiently depolarized.
DepersonalizationDepersonalization can consist of a detachment within the self, regarding one's mind or body, or being a detached observer of oneself. Subjects feel they have changed and that the world has become vague, dreamlike, less real, lacking in significance or being outside reality while looking in. It can be described as feeling like one is on “autopilot” and that the person's sense of individuality or selfhood has been hindered or suppressed.
AddictionAddiction is generally a neuropsychological disorder defining pervasive and intense urge to engage in maladaptive behaviors providing immediate sensory rewards (e.g. consuming drugs, excessively gambling), despite their harmful consequences. Dependence is generally an addiction that can involve withdrawal issues. Addictive disorder is a category of mental disorders defining important intensities of addictions or dependences, which induce functional disabilities. There are no agreed definitions on these terms – see section on 'definitions'.
DepressantDepressants, or central depressants, are drugs that lower neurotransmission levels, or depress or reduce arousal or stimulation in various areas of the brain. Depressants are also colloquially referred to as "downers" as they lower the level of arousal when taken. Depressants do not change the mood or mental state of others. Stimulants, or "uppers," increase mental or physical function, hence the opposite drug class from depressants are stimulants, not antidepressants.
AnestheticAn anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia — in other words, to result in a temporary loss of sensation or awareness. They may be divided into two broad classes: general anesthetics, which result in a reversible loss of consciousness, and local anesthetics, which cause a reversible loss of sensation for a limited region of the body without necessarily affecting consciousness. A wide variety of drugs are used in modern anesthetic practice.
HallucinationA hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combination of two conscious states of brain wakefulness and REM sleep. They are distinguishable from several related phenomena, such as dreaming (REM sleep), which does not involve wakefulness; pseudohallucination, which does not mimic real perception, and is accurately perceived as unreal; illusion, which involves distorted or misinterpreted real perception; and , which does not mimic real perception, and is under voluntary control.
DrugA drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhalation, injection, smoking, ingestion, absorption via a patch on the skin, suppository, or dissolution under the tongue. In pharmacology, a drug is a chemical substance, typically of known structure, which, when administered to a living organism, produces a biological effect.
Κ-opioid receptorThe κ-opioid receptor or kappa opioid receptor, abbreviated KOR or KOP for its ligand ketazocine, is a G protein-coupled receptor that in humans is encoded by the OPRK1 gene. The KOR is coupled to the G protein Gi/G0 and is one of four related receptors that bind opioid-like compounds in the brain and are responsible for mediating the effects of these compounds. These effects include altering nociception, consciousness, motor control, and mood. Dysregulation of this receptor system has been implicated in alcohol and drug addiction.
Nitrous oxideNitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, nitro, or nos, is a chemical compound, an oxide of nitrogen with the formula N2O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen. Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain-reducing effects.
Hallucinogen persisting perception disorderHallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after a previous use of drugs, including but not limited to psychedelics, dissociatives, entactogens, tetrahydrocannabinol (THC), and SSRIs. Despite being designated as a hallucinogen-specific disorder, the specific contributory role of psychedelic drugs is unknown.
DerealizationDerealization is an alteration in the perception of the external world, causing those with the condition to perceive it as unreal, distant, distorted or falsified. Other symptoms include feeling as if one's environment is lacking in spontaneity, emotional coloring, and depth. It is a dissociative symptom that may appear in moments of severe stress. Derealization is a subjective experience pertaining to a person's perception of the outside world, while depersonalization is a related symptom characterized by dissociation towards one's own body and mental processes.
