4-HO-PiPT, also known as 4-hydroxy-N-propyl-N-isopropyltryptamine or as piprocin, is a substituted tryptamine derivative which is claimed to have psychedelic effects. It has been encountered as a novel designer drug.
4-HO-EPT was not included nor mentioned in Alexander Shulgin's book TiHKAL (Tryptamines I Have Known and Loved).
4-HO-PiPT acts as a serotonin 5-HT<sub>2A</sub> receptor agonist, with an of 13.8nM and an efficacy of 104.8%.
Analogues of 4-HO-PiPT include propylisopropyltryptamine (PiPT), 5-MeO-PiPT, 4-HO-MiPT, 4-HO-EiPT, 4-HO-EiBT, 4-HO-DiPT, 4-HO-DsBT, 4-HO-McPT, and 4-HO-McPeT, among others.
4-HO-PiPT has been sold as a designer drug, first being identified in 2021 in British Columbia, Canada.
4-HO-PiPT is not a controlled substance in Canada as of 2025.