Clinical data
Routes of
Oral, IV, intranasal, rectal
ATC code none
Legal status
Legal status
  • AU: S9 (Prohibited)
  • CA: Unscheduled
  • UK: Class A
  • US: Unscheduled as a lab reagent; however, it is an acetate ester of psilocin, meaning it would be considered Schedule I under the Federal Analogue Act[1] when sold for in vivo use.
Synonyms 4-Acetoxy-N,N-dimethyltryptamine, 3-(2'-dimethylaminoethyl)-4-acetoxy-indole[2]
CAS Number 92292-84-7 YesY
PubChem (CID) 15429212
ChemSpider 21106357 YesY
Chemical and physical data
Formula C14H18N2O2
Molar mass 246.3049 g/mol
3D model (Jmol) Interactive image
Melting point 172 to 173 °C (342 to 343 °F)

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.[3] However, some users report that O-acetylpsilocin's subjective effects differ from that of psilocybin and psilocin.[4] 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.[2][5] Despite this, 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. This is because the aromatic acetyl moiety on the 4th position is subject to deacetylation by acidic conditions such as those found in the stomach.[6] 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.[3]


See psilocin for more details.

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

Claims of subjective differences in effect between the acetylated and not acetylated forms of psilocin;[4] 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. Despite this, there have been no controlled clinical studies to distinguish the effects between psilacetin, psilocin, and psilocybin.

4-AcO-DMT shown in powder form


United Kingdom

O-Acetylpsilocin is illegal in the UK under the Misuse of Drugs Act 1971.


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


O-Acetylpsilocin can be considered an analog of psilocin making it a schedule 9 prohibited substance in Australia under the Poisons Standard (October 2015).[7] 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.[7]

See also


  1. Federal Analogue Act
  2. 1 2 US patent 3075992, Hofmann A, Troxler F, "Esters of indoles", assigned to Sandoz Ltd.
  3. 1 2 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. doi:10.1055/s-1999-3490. ISSN 0039-7881. Retrieved 17 January 2012.
  4. 1 2 http://www.erowid.org/experiences/subs/exp_4AcODMT.shtml
  5. US 3075992
  6. Stanek, J.; Cerna, Jitka (1963). Acidic deacetylation of sugar acetates. Tetrahedron, 35-7,ISSN 0040-4039. Retrieved 16 June 2016.
  7. 1 2 Poisons Standard October 2015 https://www.comlaw.gov.au/Details/F2015L01534
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