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). It was encountered as a novel designer drug in Japan by 2021.
4-HO-EPT was not included nor mentioned in Alexander Shulgin's book TiHKAL (Tryptamines I Have Known and Loved). 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 30mg orally.
4-HO-EPT is a potent full agonist of the serotonin 5-HT<sub>2A</sub>, 5-HT<sub>2B</sub>, and 5-HT<sub>2C</sub> receptors. It has one to two orders of magnitude greater potency as a serotonin 5-HT<sub>2A</sub> and 5-HT<sub>2B</sub> receptor agonist than as a serotonin 5-HT<sub>2C</sub> receptor agonist. The drug also shows affinity for other serotonin receptors, such as the serotonin 5-HT<sub>1A</sub> and 5-HT<sub>6</sub> receptors. 4-HO-EPT produces the head-twitch response, a behavioral proxy of psychedelic effects, in rodents.
The metabolism of 4-HO-EPT has been studied.
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.
4-HO-EPT is not a controlled substance in Canada as of 2025.
4-HO-EPT is illegal in the United Kingdom as a result of the Psychoactive Substances Act of 2016.
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.