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O-Acetylpsilocin chemical structure.png
Systematic (IUPAC) name
3-[2-(Dimethylamino)ethyl]-1H-indol-4-yl acetate
Clinical data
Legal status Unscheduled (CA)
Unscheduled (US)
May be considered Illegal if intended for human consumption
Routes Oral, IV, intranasal, rectal
CAS number 92292-84-7 7pxY
ATC code None
PubChem CID 15429212
ChemSpider 21106357 7pxY
Synonyms 4-acetoxy-N,N-dimethyltryptamine, 3-(2'-dimethylaminoethyl)-4-acetoxy-indole[1]
Chemical data
Formula C14H18N2O2 
Mol. mass 246.3049 g/mol
Physical data
Melt. point 172–173 °C (342–343 °F)
 14pxY (what is this?)  (verify)

O-Acetylpsilocin (also known as Psilacetin, 4-Acetoxy-DMT, or 4-AcO-DMT) is a synthetically produced psychoactive drug and 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] However, many report that O-Acetylpsilocin's effects differ greatly from that of psilocybin and psilocin.[3] It is the acetylated form of the psilocybin mushroom alkaloid psilocin, and is a lower homologue of 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 (US Patent # 3,075,992).[1] Despite this fact, psilacetin remains a psychedelic with a limited history of use. It is theorized to be a prodrug for psilocin, as is psilocybin, which is naturally occurring in various mushrooms. 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 a synthetic compound. However, it is believed to be a prodrug of psilocin, which is natural and occurs in many mushrooms along with psilocybin. O-Acetylpsilocin is more resistant than psilocin to oxidation under basic conditions due to its acetoxy group. While O-acetylpsilocin is not well researched (considered by many to be a research chemical, as opposed to psilocin and psilocybin), it is not as difficult to produce as psilocybin, and may be an appropriate substitute for psilocybin in psychedelic research because of their similar mechanism of action.[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). Its ability to alter cellular metabolism by competing for the deacetylase enzyme causes a perceptible loss of cellular heat generation capacity at doses between 0.4 and 0.8mmol.

Claims of subjective differences in effect between the acetylated and not acetylated forms of psilocin;[3] some users report that O-acetylpsilocin lasts slightly longer; others report that it lasts for a considerably shorter time. Many users report less body load and nausea compared to psilocin. Some users find that the visual distortions produced by O-acetylpsilocin more closely resemble those produced by DMT than those produced by psilocin. These differences could be possible if psilacetin is active itself and not merely as a prodrug.


A dose of O-acetylpsilocin is 8 mg - 30 mg.[citation needed] These are slightly lower than that psilocin. Some report very strong effects with 15 mg. A dose of 15 mg can produce a very profound experience, with effects such as ego loss, strong visuals (open and closed eye), and other effects similar to a high dose of psilocin. Comparison to psilocin dosage suggests that O-acetylpsilocin is somewhat more potent, and possibly more variable in terms of subjective susceptibility. O-Acetylpsilocin seems to have a more steep dose-effect curve than psilocin; therefore, caution should be taken, especially with higher doses. There is no known LD50, as there are no reported cases of fatal overdose. Human testing has determined the most likely cause of death in overdose to be hypothermia.[citation needed]

Dosages vary slightly depending on the type of salt. The hydrochloride has a higher molecular mass and is therefore less potent on a per weight basis than its freebase form; however, freebase O-acetylpsilocin is relatively unstable and will degrade quickly at room temperature. O-Acetylpsilocin is now most commonly distributed as the fumaric acid salt (O-acetylpsilocin fumarate). The fumarate is even less potent on a per weight basis, but is also considerably more stable and will not degrade substantially at room temperature. The ratio of hydrochloride to fumarate is approximately .93:1.

O-Acetylpsilocin fumarate Oral Dose Intranasal
Threshold 4 mg-7 mg 2 mg-4 mg
Light 8 mg-12 mg 3 mg-10 mg
Common 13 mg-17 mg 8 mg-18 mg
Strong 18 mg-23 mg 15 mg-25 mg
Heavy 24 mg+ 29 mg+

These above doses are taken from the site erowid.org, which advises potential users of this chemical as a psychedelic drug: "Please note that the above doses should only be used as a general outline. This chemical is still relatively new, with a short history of human use. Every individual reacts differently to every chemical."


O-Acetylpsilocin is theorized to be metabolized into psilocin, as such is the case with psilocybin;[citation needed] however, reports indicate that O-acetylpsilocin may be active on its own.[citation needed] The effects of O-acetylpsilocin are therefore somewhat similar to the effects of psilocybin and psilocin.[medical citation needed]


  • Brightened colors / enhanced visual perception
  • Introspection and philosophical insights
  • Stimulation/ sensation / tingling (serotonin system)
  • Euphoria
  • Perceptual enhancement
  • Empathy
  • Sexual arousal


Negative effects

  • Mild to severe anxiety
  • Shivering
  • Paranoia
  • Stomach discomfort
  • Insomnia
  • Overly-intense experience (at high doses)
  • Overwhelming ideas and/or racing thoughts
  • Difficulty speaking
  • Motor impairment, vertigo
  • Confusion
  • Significantly elevated heart rate
  • Hypothermia


The onset starts 20–40 minutes after ingestion, with peak effects beginning after 40-60 minutes and lasting 2-3 hours. Total duration from ingestion to baseline is approximately 4-5 hours on an empty stomach.


The visuals are quite mild at average doses, with mental effects dominating primarily. With closed eyes a person may perceive patterns, colors, and strange, sometimes intense subconscious awareness (perceived in a visual way). Open eyed visuals are fleeting and consist of slight movement, especially peripherally, and increased color intensity. At higher doses, full hallucinations are not uncommonly reported, but not consistent. Above 25 mg the visuals are reported to gain intensity and can include very complex geometric and dynamic patterns, "melting" of objects and loss of object comprehension (as if perceiving objects for the first time or in a new way).


O-Acetylpsilocin is unscheduled in the United States. It may be considered an analog of psilocin, which is a Schedule I drug under the Controlled Substances Act of the USA, and as such sale for human consumption or possession to ingest or use for illicit non-medical or industrial intents and purposes could be prosecuted as crimes under the Federal Analog Act.

O-Acetylpsilocin could also be considered illegal in the UK under the Misuse of Drugs Act 1971. Ester derivatives of prohibited substances also hold criminal penalties. O-Acetylpsilocin is an ester of psilocin, to which it metabolizes. This means that it potentially carries the same penalty as any Class A drug, such as heroin or cocaine.

See also


  1. 1.0 1.1 US patent 3075992, Hofmann A, Troxler F, "Esters of indoles", assigned to Sandoz Ltd. 
  2. 2.0 2.1 Nichols, David; Fescas, Stewart (1999). "Improvements to the Synthesis of Psilocybin and a Facile Method for Preparing the O-Acetyl Prodrug of Psilocin" (PDF). Synthesis (Stuttgart · New York: Thieme) (6): 935–938. ISSN 0039-7881. Retrieved 17 January 2012. 
  3. 3.0 3.1 http://www.erowid.org/experiences/subs/exp_4AcODMT.shtml

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