Last updated
O-Acetylpsilocin chemical structure.png
Clinical data
Other names4-Acetoxy-N,N-dimethyltryptamine, 3-(2'-dimethylaminoethyl)-4-acetoxy-indole [1]
Routes of
Oral, IV, intranasal, rectal
ATC code
  • none
Legal status
Legal status
  • AU: S9 (Prohibited substance)
  • CA:Unscheduled
  • DE: NpSG (Industrial and scientific use only)
  • UK: Class A
  • US:Unscheduled
  • 3-[2-(Dimethylamino)ethyl]-1H-indol-4-yl acetate
CAS Number
PubChem CID
CompTox Dashboard (EPA)
Chemical and physical data
Formula C14H18N2O2
Molar mass 246.310 g·mol−1
3D model (JSmol)
Melting point 172 to 173 °C (342 to 343 °F)
  • CC(=O)Oc2cccc1[nH]cc(CCN(C)C)c12
  • InChI=1S/C14H18N2O2/c1-10(17)18-13-6-4-5-12-14(13)11(9-15-12)7-8-16(2)3/h4-6,9,15H,7-8H2,1-3H3 Yes check.svgY

O-Acetylpsilocin (also known as psilacetin, 4-acetoxy-DMT, 4-AcO-DMT, or synthetic shrooms) is a semi-synthetic psychoactive drug that has been suggested by David Nichols to be a potentially useful alternative to psilocybin for pharmacological studies, as they are both believed to be prodrugs of psilocin. [2] [3] However, some users report that O-acetylpsilocin's subjective effects differ from those of psilocybin and psilocin. [4] [5] Additionally, some users prefer 4-AcO-DMT to natural psilocybin mushrooms due to feeling fewer adverse side effects such as nausea and heavy body load, which are more frequently reported in experiences involving natural mushrooms. [6] It is the acetylated form of the psilocybin mushroom alkaloid psilocin and is a lower homolog of 4-AcO-MET, 4-AcO-DET, 4-AcO-MiPT and 4-AcO-DiPT.



O-Acetylpsilocin (psilacetin) and several other esters of psilocin were patented on January 16, 1963 by Sandoz Ltd via Albert Hofmann & Franz Troxler. [1] [7] Despite this, psilacetin remains a psychedelic compound with a limited history of use. It is theorized to be a prodrug of psilocin, as is psilocybin, which occurs naturally in many species of hallucinogenic mushrooms. This is because the aromatic acetyl moiety on the 4th position of the indole ring system is subject to deacetylation in acidic conditions such as those found in the stomach. [8] Psilacetin is O-acetylated psilocin, whereas psilocybin is O-phosphorylated.


O-Acetylpsilocin can be obtained by acetylation of psilocin under alkaline or strongly acidic conditions. It is, therefore, a synthetic compound. It is believed to be a prodrug of psilocin; however, speculation exists that psilacetin itself also may be psychoactive. O-Acetylpsilocin is more resistant than psilocin to oxidation under basic conditions due to its acetoxy group. While O-acetylpsilocin is not well researched (sometimes viewed negatively as a research chemical, as opposed to psilocin and psilocybin), it is not as difficult as psilocybin to synthesize. Due to their similar proposed mechanisms of action, this factor may provide further support for the proposition that O-acetylpsilocin might serve as an appropriate substitute for psilocybin in research of the application of psychedelic compounds in medicine. [2]


See psilocin for more details.

In the body O-acetylpsilocin is deacetylated to psilocin by deacetylases/acetyltransferases during first pass metabolism [ citation needed ] and during subsequent passes through the liver (evident as psilacetin is also active via parenteral routes of ingestion).

Claims of subjective differences in effects between the acetylated and non-acetylated forms of psilocin vary: [4] some users report that O-acetylpsilocin lasts slightly longer, whilst others report that it lasts for a considerably shorter time. Many users report less body load and nausea compared with psilocin. Some users find that the visual effects produced by O-acetylpsilocin more closely resemble those produced by DMT than those produced by psilocin or psilocybin. These differences could be possible if psilacetin is psychoactive in itself and not merely as a prodrug. Despite this, there have been no controlled clinical studies to distinguish among the phenomenological effects of psilacetin, psilocin, and psilocybin.

4-AcO-DMT shown in powder form 4-AcO-DMT 1g.png
4-AcO-DMT shown in powder form



O-Acetylpsilocin can be considered an analog of psilocin making it a Schedule 9 prohibited substance in Australia under the Poisons Standard (October 2015). [9] A Schedule 9 substance is a substance which may be abused or misused, the manufacture, possession, sale or use of which should be prohibited by law except when required for medical or scientific research, or for analytical, teaching or training purposes with approval of Commonwealth and/or State or Territory Health Authorities. [9]

United States

O-Acetylpsilocin is ambiguously legal for use as a lab reagent or research chemical; however, it is an acetate ester of psilocin, meaning it would be considered akin to a Schedule I Controlled Substance under the Federal Analogue Act if sold for human consumption.

United Kingdom

O-Acetylpsilocin, being an ester of psilocin, is a Class A drug in the UK under the Misuse of Drugs Act 1971. [10]


O-Acetylpsilocin is illegal in Italy as it is an ester of a prohibited substance.


The Riksdag added 4-AcO-DMT to Narcotic Drugs Punishments Act under swedish schedule I ("substances, plant materials and fungi which normally do not have medical use" ) as of January 25, 2017, published by Medical Products Agency (MPA) in regulation HSLF-FS 2017:1 listed as 4-acetoxi-N,N-dimetyltryptamin. [11]


O-Acetylpsilocin is technically illegal in Israel as of being a derivative of DMT.

See also

Related Research Articles

<span class="mw-page-title-main">Recreational drug use</span> Use of drugs with the primary intention to alter the state of consciousness

Recreational drug use is the use of one or more psychoactive drugs to induce an altered state of consciousness either for pleasure or for some other casual purpose or pastime. When a psychoactive drug enters the user's body, it induces an intoxicating effect. Generally, recreational drugs are divided into three categories: depressants, stimulants, and hallucinogens.

<span class="mw-page-title-main">Psilocybin</span> Chemical compound found in some species of mushrooms

Psilocybin is a naturally occurring psychedelic prodrug compound produced by more than 200 species of fungi. The most potent are members of genus Psilocybe, such as P. azurescens, P. semilanceata, and P. cyanescens, but psilocybin has also been isolated from about a dozen other genera. Psilocybin is itself biologically inactive but is quickly converted by the body to psilocin, which has mind-altering effects similar, in some aspects, to those of lysergic acid diethylamide (LSD), mescaline, and dimethyltryptamine (DMT). In general, the effects include euphoria, visual and mental hallucinations, changes in perception, distorted sense of time, and perceived spiritual experiences. It can also cause adverse reactions such as nausea and panic attacks.

<span class="mw-page-title-main">Psychedelic drug</span> Hallucinogenic class of psychoactive drug

Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary mental states and/or an apparent expansion of consciousness. Sometimes, they are called classic hallucinogens, serotonergic hallucinogens, or serotonergic psychedelics, and the term psychedelic is sometimes used more broadly to include various types of hallucinogens or those which are atypical or adjacent to psychedelia such as MDMA or cannabis; this article uses the narrower definition of psychedelics. True psychedelics cause specific psychological, visual, and auditory changes, and oftentimes a substantially altered state of consciousness. Psychedelic states are often compared to meditative, psychodynamic or transcendental types of alterations of the mind. The "classical" psychedelics, the psychedelics with the largest scientific and cultural influence, are mescaline, LSD, psilocybin, and DMT. In particular, LSD has long been considered the paradigmatic psychedelic compound to which all other psychedelics are often or usually compared.

<i>Psilocybe cubensis</i> Species of fungus

Psilocybe cubensis is a species of psilocybin mushroom of moderate potency whose principal active compounds are psilocybin and psilocin. Commonly called shrooms, magic mushrooms, golden halos, cubes, or gold caps, it belongs to the fungus family Hymenogastraceae and was previously known as Stropharia cubensis. It is the best-known psilocybin mushroom due to its wide distribution and ease of cultivation. This mushroom being optimal for home cultivation specifically, as was suggested in the 1970s, is primarily what led to cubensis being the psilocybin mushroom species most common on the black market as a street drug.

<span class="mw-page-title-main">Psilocybin mushroom</span> Mushrooms containing psychoactive indole alkaloids

Psilocybin mushrooms, commonly known as magic mushrooms, are a polyphyletic informal group of fungi that contain psilocybin which turns into psilocin upon ingestion. Biological genera containing psilocybin mushrooms include Psilocybe, Panaeolus, Inocybe, Pluteus, Gymnopilus, and Pholiotina. Psilocybin mushrooms have been and continue to be used in indigenous New World cultures in religious, divinatory, or spiritual contexts. They are also used as recreational drugs. They may be depicted in Stone Age rock art in Africa and Europe, but are most famously represented in the Pre-Columbian sculptures and glyphs seen throughout North, Central and South America.

<i>Psilocybe</i> Genus of fungi

Psilocybe is a genus of gilled mushrooms, growing worldwide, in the family Hymenogastraceae. Most or nearly all species contain the psychedelic compounds psilocybin and psilocin.

<span class="mw-page-title-main">5-MeO-DMT</span> Chemical compound

5-MeO-DMT (5-methoxy-N,N-dimethyltryptamine) or O-methyl-bufotenin is a psychedelic of the tryptamine class. It is found in a wide variety of plant species, and also is secreted by the glands of at least one toad species, the Colorado River toad. Like its close relatives DMT and bufotenin (5-HO-DMT), it has been used as an entheogen in South America. Slang terms include Five-methoxy, the power, bufo, and toad venom.

<span class="mw-page-title-main">4-HO-DiPT</span> Chemical compound

4-Hydroxy-N,N-diisopropyltryptamine is a synthetic psychedelic drug. It is a higher homologue of psilocin, 4-HO-DET, and is a positional isomer of 4-HO-DPT and has a tryptamine molecular sub-structure.

<span class="mw-page-title-main">Psilocin</span> Chemical compound

Psilocin is a substituted tryptamine alkaloid and a serotonergic psychedelic substance. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocybin. Psilocin is a Schedule I drug under the Convention on Psychotropic Substances. Acting on the 5-HT2A receptors, psilocin modulates the production and reuptake of serotonin. The mind-altering effects of psilocin are highly variable and subjective and resemble those of LSD and DMT.

<span class="mw-page-title-main">Diethyltryptamine</span> Chemical compound

DET, also known under its chemical name N,N-diethyltryptamine and as T-9, is a psychedelic drug closely related to DMT and 4-HO-DET. However, despite its structural similarity to DMT, its activity is induced by an oral dose of around 50–100 mg, without the aid of MAO inhibitors, and the effects last for about 2–4 hours.

<span class="mw-page-title-main">4-HO-DET</span> Chemical compound

4-HO-DET, also known as 4-hydroxy-diethyl-tryptamine, CZ-74, is a hallucinogenic drug and psychedelic compound of moderate duration. 4-HO-DET is a substituted tryptamine, structurally related to psilocin, ethocybin, and 4-HO-DIPT.

<span class="mw-page-title-main">4-HO-MiPT</span> Chemical compound

4-HO-MiPT is a synthetic substituted aromatic compound and a lesser-known psychedelic tryptamine. It is thought to be a serotonergic psychedelic, similar to magic mushrooms, LSD and mescaline. Its molecular structure and pharmacological effects somewhat resemble those of the tryptamine psilocin, which is the primary psychoactive chemical in magic mushrooms.

<span class="mw-page-title-main">Ethocybin</span> Chemical compound

Ethocybin is a homologue of the mushroom alkaloid psilocybin, and a semi-synthetic psychedelic alkaloid of the tryptamine family. Effects of ethocybin are comparable to those of a shorter LSD or psilocybin trip, although intensity and duration vary depending on dosage, individual physiology, and set and setting.

<span class="mw-page-title-main">4-HO-MET</span> Chemical compound

4-HO-MET, is a lesser-known psychedelic drug. It is a structural− and functional analog of psilocin as well as the 4-hydroxyl analog of methylethyltryptamine (MET). 4-HO-MET was first synthesized by Alexander Shulgin. In his book TiHKAL, the dosage is listed as 10-20 mg. 4-HO-MET produces psilocin-like distortion of color, sound, and form. Very little data exists about the pharmacological properties, metabolism, and toxicity of 4-HO-MET. There have been no reports of deaths from 4-HO-MET, even though people have reported taking doses up to 150 mg, more than an order of magnitude above the effective dose.

The legal status of unauthorised actions with psilocybin mushrooms varies worldwide. Psilocybin and psilocin are listed as Schedule I drugs under the United Nations 1971 Convention on Psychotropic Substances. Schedule I drugs are defined as drugs with a high potential for abuse or drugs that have no recognized medical uses. However, psilocybin mushrooms have had numerous medicinal and religious uses in dozens of cultures throughout history and have a significantly lower potential for abuse than other Schedule I drugs.

<span class="mw-page-title-main">4-HO-αMT</span> Chemical compound

4-Hydroxy-α-methyltryptamine (4-HO-αMT) is a psychedelic drug of the tryptamine class. It is a close structural analogue of α-methyltryptamine (αMT) and produces similar effects to it, but with exacerbated side effects similarly to 5-MeO-αMT. Alexander Shulgin describes 4-HO-αMT briefly in his book TiHKAL:

The 4-hydroxy analogue of αMT has been looked at in human subjects. It is reported to be markedly visual in its effects, with some subjects reporting dizziness and a depressed feeling. There were, however, several toxic signs at doses of 15 to 20 milligrams orally, including abdominal pain, tachycardia, increased blood pressure and, with several people, headache and diarrhea.

<span class="mw-page-title-main">Substituted tryptamine</span> Class of indoles

Substituted tryptamines, or serotonin analogues, are organic compounds which may be thought of as being derived from tryptamine itself. The molecular structures of all tryptamines contain an indole ring, joined to an amino (NH2) group via an ethyl (−CH2–CH2−) sidechain. In substituted tryptamines, the indole ring, sidechain, and/or amino group are modified by substituting another group for one of the hydrogen (H) atoms.

<span class="mw-page-title-main">4-Acetoxy-MET</span> Chemical compound

4-Acetoxy-MET (4-Acetoxy-N-methyl-N-ethyltryptamine), also known as metacetin or 4-AcO-MET, is a hallucinogenic tryptamine. It is the acetate ester of 4-HO-MET, and a homologue of 4-AcO-DMT. It is a novel compound with very little history of human use. It is sometimes sold as a research chemical by online retailers.

<span class="mw-page-title-main">Psilocybin therapy</span> Experimental use of psilocybin to treat anxiety & depression

Psilocybin therapy is the use of psilocybin in treating a range of mental health conditions, such as depression, anxiety, addictions, obsessive compulsive disorder, and psychosis. It is one of several forms of psychedelic therapy under study. Psilocybin was popularized as a psychedelic recreational drug in the 1970s and was classified as a Schedule I drug by the DEA. Research on psilocybin as a medical treatment was restricted until the 1990s because of the sociocultural fear of dependence on this drug. As of 2022, psilocybin is the most commonly researched psychedelic due to its safety and low potential for abuse and dependence. Clinical trials are being conducted at universities and there is evidence confirming the use of psilocybin in the treatment of depression, PTSD and end of life anxiety.

<span class="mw-page-title-main">4-PrO-DMT</span> Chemical compound

4-Propionoxy-N,N-dimethyltryptamine is a synthetic psychedelic drug from the tryptamine family with psychedelic effects, and is believed to act as a prodrug for psilocin. It produces a head-twitch response in mice. It has been sold online as a designer drug since May 2019. It was first identified as a new psychoactive substance in Sweden, in July 2019.


  1. 1 2 USpatent 3075992,Hofmann A, Troxler F,"Esters of indoles", assigned to Sandoz Ltd.
  2. 1 2 Nichols D, Fescas S (1999). "Improvements to the Synthesis of Psilocybin and a Facile Method for Preparing the O-Acetyl Prodrug of Psilocin" (PDF). Synthesis. 1999 (6): 935–938. CiteSeerX . doi:10.1055/s-1999-3490. S2CID   32044725. Archived (PDF) from the original on 17 February 2012. Retrieved 17 January 2012.
  3. Bauer BE (2019-09-18). "The State of the Art of Psilacetin (4-AcO-DMT)". Psychedelic Science Review. Retrieved 2021-02-13.
  4. 1 2 "4-AcO-DMT (also 4-acetoxy-N,N-dimethyltryptamine) : Erowid Exp: Main Index". www.erowid.org. Archived from the original on 2010-07-28.
  5. Janikian M (2020-05-26). "The Complete Guide: 4-AcO-DMT a.k.a. Synthetic Shrooms". DoubleBlind Mag.
  6. Palamar JJ, Acosta P (January 2020). "A qualitative descriptive analysis of effects of psychedelic phenethylamines and tryptamines". Human Psychopharmacology. 35 (1): e2719. doi:10.1002/hup.2719. PMC   6995261 . PMID   31909513.
  7. US 3075992
  8. Staněk J, Černá MJ (January 1963). "Acidic deacetylation of sugar acetates". Tetrahedron Letters. 4 (1): 35–7. doi:10.1016/S0040-4039(01)90572-6.
  9. 1 2 "Poisons Standard October 2015". Federal Register of Legislation. Australian Government. Archived from the original on 2016-01-19. Retrieved 2016-01-06.
  10. "Misuse of Drugs Act 1971". Schedule 2 Part I, Act of 1971.
  11. "Föreskrifter om ändring i Läkemedelsverkets föreskrifter (LVFS 2011:10) om förteckningar över narkotika" [Regulations on changes in the Swedish Medicines Agency's regulations (LVFS 2011:10) on lists of narcotics](PDF) (in Northern Sami). Archived (PDF) from the original on 2017-10-31. Retrieved 2017-04-21.