4-HO-EPT

4-HO-EPT
Clinical data
Other names	4-OH-EPT; 4-Hydroxy-N-ethyl-N-propyltryptamine; Eprocin
Routes of; administration	Oral
Drug class	Non-selective serotonin receptor agonist; Serotonin 5-HT2A receptor agonist; Serotonergic psychedelic; Hallucinogen
ATC code	None;
Identifiers
	IUPAC name 3-{2-[ethyl(propyl)amino]ethyl}-1H-indol-4-ol;
CAS Number	2595431-59-5 N[PubChem];
PubChem CID	138454310;
ChemSpider	129433801;
UNII	Y3J8M5UX6G;
CompTox Dashboard (EPA)	DTXSID801336292 ;
Chemical and physical data
Formula	C15H22N2O
Molar mass	246.354 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES CCCN(CC)CCC1=CNC2=CC=CC(O)=C12;
	InChI InChI=1S/C15H22N2O/c1-3-9-17(4-2)10-8-12-11-16-13-6-5-7-14(18)15(12)13/h5-7,11,16,18H,3-4,8-10H2,1-2H3; Key:JQELEPKHBXEAHR-UHFFFAOYSA-N;

Pharmaceutical compound

4-HO-EPT, also known as 4-hydroxy-N-ethyl-N-propyltryptamine or as eprocin, is a psychedelic drug of the tryptamine family, which is structurally related to psilocin (4-HO-DMT).^[1] It was encountered as a novel designer drug in Japan by 2021.^[1]

Use and effects

4-HO-EPT was not included nor mentioned in Alexander Shulgin's book TiHKAL (Tryptamines I Have Known and Loved).^[2] Subsequently, however, an assumed prodrug of 4-HO-EPT, 4-AcO-EPT, has emerged as a novel designer drug, and has been said based on online anecdotal reports to have a dose of 20 to 30 mg orally.^[3]^[4]

Interactions

Pharmacology

Pharmacodynamics

4-HO-EPT activities
Target	Affinity (K_i, nM)
5-HT_1A	163
5-HT_1B	1,097
5-HT_1D	644
5-HT_1E	591
5-HT_2A	546 (K_i) 3.2 (EC₅₀Tooltip half-maximal effective concentration) 100% (E_maxTooltip maximal efficacy)
5-HT_2B	62 (K_i) 4.3 (EC₅₀) 89% (E_max)
5-HT_2C	1,272 (K_i) 129 (EC₅₀) 89% (E_max)
5-HT_5A	1,576
5-HT₆	284
5-HT₇	438
α_2A	2,073
α_2B, α_2C	>10,000
D₂	3,010
D₃	985
D₄, D₅	>10,000
H₁	406
H₂	>10,000
M₄	>10,000
σ₁	1,400
σ₂	1,773
KORTooltip κ-Opioid receptor	>10,000
NR2B	5,947
SERTTooltip Serotonin transporter	1,257
DATTooltip Dopamine transporter	>10,000
Notes: The smaller the value, the more avidly the drug interacts with the site. Sources: ^[5]^[6]

4-HO-EPT is a potent full agonist of the serotonin 5-HT_2A, 5-HT_2B, and 5-HT_2C receptors.^[5]^[6] It has one to two orders of magnitude greater potency as a serotonin 5-HT_2A and 5-HT_2B receptor agonist than as a serotonin 5-HT_2C receptor agonist.^[5] The drug also shows affinity for other serotonin receptors, such as the serotonin 5-HT_1A and 5-HT₆ receptors.^[6] 4-HO-EPT produces the head-twitch response, a behavioral proxy of psychedelic effects, in rodents.^[5]

Pharmacokinetics

The metabolism of 4-HO-EPT has been studied.^[7]

Chemistry

Analogues

Analogues of 4-HO-EPT include ethylpropyltryptamine (EPT), 5-MeO-EPT, 5-fluoro-EPT, 4-HO-MPT, 4-HO-PiPT, 4-HO-DET, and 4-HO-DPT, among others.

Society and culture

Legal status

4-HO-EPT is not a controlled substance in Canada as of 2025.^[8]

United Kingdom

4-HO-EPT is illegal in the United Kingdom as a result of the Psychoactive Substances Act of 2016.^[9]

United States

4-HO-EPT may be considered an analogue of psilocin, which is a Schedule I drug under the Controlled Substances Act. As such, the sale for human consumption would be illegal under the Federal Analogue Act.^{[citation needed]}

References

1 2 Tanaka R, Kawamura M, Hakamatsuka T, Kikura-Hanajiri R (2021). "Identification of six tryptamine derivatives as designer drugs in illegal products". Forensic Toxicology. 39 (1): 248–258. doi:10.1007/s11419-020-00556-5. ISSN 1860-8965. Retrieved 9 October 2025.
↑ Shulgin A, Shulgin A (September 1997). TiHKAL: The Continuation. Berkeley, California: Transform Press. ISBN 0-9630096-9-9. OCLC 38503252.
↑ "4-OH-EPT AC (4-AcO-EPT)". АИПСИН (in Russian). Retrieved 2 January 2026.
↑ "4-HO-EPT AC (4-AcO-EPT)". АИПСИН (in Russian). Retrieved 2 January 2026.
1 2 3 4 Klein AK, Chatha M, Laskowski LJ, Anderson EI, Brandt SD, Chapman SJ, et al. (April 2021). "Investigation of the Structure-Activity Relationships of Psilocybin Analogues". ACS Pharmacology & Translational Science. 4 (2): 533–542. doi:10.1021/acsptsci.0c00176. PMC 8033608. PMID 33860183.
1 2 3 Glatfelter GC, Naeem M, Pham DN, Golen JA, Chadeayne AR, Manke DR, et al. (April 2023). "Receptor Binding Profiles for Tryptamine Psychedelics and Effects of 4-Propionoxy-N,N-dimethyltryptamine in Mice". ACS Pharmacology & Translational Science. 6 (4): 567–577. doi:10.1021/acsptsci.2c00222. PMC 10111620. PMID 37082754.
↑ Bergh MS, Bogen IL, Grafinger KE, Huestis MA, Øiestad ÅM (December 2024). "Metabolite markers for three synthetic tryptamines N-ethyl-N-propyltryptamine, 4-hydroxy-N-ethyl-N-propyltryptamine, and 5-methoxy-N-ethyl-N-propyltryptamine". Drug Testing and Analysis. 16 (12): 1544–1557. doi:10.1002/dta.3668. PMC 11635065. PMID 38459837.
↑ "Controlled Drugs and Substances Act". Department of Justice Canada. Retrieved 19 January 2026.
↑ "Misuse of Drugs Act 1971 (Legislation.gov.uk)".

[Tanaka_2021-1] 1 2 Tanaka R, Kawamura M, Hakamatsuka T, Kikura-Hanajiri R (2021). "Identification of six tryptamine derivatives as designer drugs in illegal products". Forensic Toxicology. 39 (1): 248–258. doi:10.1007/s11419-020-00556-5. ISSN 1860-8965. Retrieved 9 October 2025.

[TiHKAL-2] Shulgin A, Shulgin A (September 1997). TiHKAL: The Continuation. Berkeley, California: Transform Press. ISBN 0-9630096-9-9. OCLC 38503252.

[Aipsin-4-AcO-EPT-3] "4-OH-EPT AC (4-AcO-EPT)". АИПСИН (in Russian). Retrieved 2 January 2026.

[Aipsin-4-AcO-EPT-2-4] "4-HO-EPT AC (4-AcO-EPT)". АИПСИН (in Russian). Retrieved 2 January 2026.

[Klein_2021-5] 1 2 3 4 Klein AK, Chatha M, Laskowski LJ, Anderson EI, Brandt SD, Chapman SJ, et al. (April 2021). "Investigation of the Structure-Activity Relationships of Psilocybin Analogues". ACS Pharmacology & Translational Science. 4 (2): 533–542. doi:10.1021/acsptsci.0c00176. PMC 8033608. PMID 33860183.

[Glatfelter_2023-6] 1 2 3 Glatfelter GC, Naeem M, Pham DN, Golen JA, Chadeayne AR, Manke DR, et al. (April 2023). "Receptor Binding Profiles for Tryptamine Psychedelics and Effects of 4-Propionoxy-N,N-dimethyltryptamine in Mice". ACS Pharmacology & Translational Science. 6 (4): 567–577. doi:10.1021/acsptsci.2c00222. PMC 10111620. PMID 37082754.

[Bergh_2024-7] Bergh MS, Bogen IL, Grafinger KE, Huestis MA, Øiestad ÅM (December 2024). "Metabolite markers for three synthetic tryptamines N-ethyl-N-propyltryptamine, 4-hydroxy-N-ethyl-N-propyltryptamine, and 5-methoxy-N-ethyl-N-propyltryptamine". Drug Testing and Analysis. 16 (12): 1544–1557. doi:10.1002/dta.3668. PMC 11635065. PMID 38459837.

[CDSA-8] "Controlled Drugs and Substances Act". Department of Justice Canada. Retrieved 19 January 2026.

[9] "Misuse of Drugs Act 1971 (Legislation.gov.uk)".

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Clinical data


Other names	4-OH-EPT; 4-Hydroxy-N-ethyl-N-propyltryptamine; Eprocin
Routes of administration	Oral
Drug class	Non-selective serotonin receptor agonist; Serotonin 5-HT_2A receptor agonist; Serotonergic psychedelic; Hallucinogen
ATC code	None
Identifiers
IUPAC name 3-{2-[ethyl(propyl)amino]ethyl}-1H-indol-4-ol
CAS Number	2595431-59-5^N[PubChem]
PubChem CID	138454310
ChemSpider	129433801
UNII	Y3J8M5UX6G
CompTox Dashboard (EPA)	DTXSID801336292
Chemical and physical data
Formula	C₁₅H₂₂N₂O
Molar mass	246.354 g·mol⁻¹
3D model (JSmol)	Interactive image
SMILES CCCN(CC)CCC1=CNC2=CC=CC(O)=C12
InChI InChI=1S/C15H22N2O/c1-3-9-17(4-2)10-8-12-11-16-13-6-5-7-14(18)15(12)13/h5-7,11,16,18H,3-4,8-10H2,1-2H3 Key:JQELEPKHBXEAHR-UHFFFAOYSA-N