4-HO-MPT, also called meprocin, is a synthetic 4-hydroxy tryptamine with one methyl and one n-propyl group attached to the terminal nitrogen. It is a higher homologue of psilocin and differs from 4-HO-MiPT by having a straight-chain propyl group rather than an isopropyl group. The compound has been included in receptor-binding and functional studies, but human evidence remains limited.
Chemistry and relationship to other tryptamines
4-HO-MPT is 4-hydroxy-N-methyl-N-propyltryptamine. It retains the 4-hydroxyindole portion found in psilocin, while the terminal nitrogen carries a methyl-propyl substitution. This places it between the smaller N,N-dimethyl compound and larger dialkyl analogues in terms of side-chain structure.
A Swedish forensic assessment recorded the compound under the name 4-hydroxy-N-methyl-N-propyltryptamine and distinguished it from 4-HO-MET, 4-HO-DiPT and other 4-substituted tryptamines (Swedish National Forensic Centre assessment of 4-HO-MPT, 2020).
Receptor pharmacology
4-HO-MPT interacts with several serotonin receptor subtypes. A broad receptor-screening study reported binding at 5-HT2A, 5-HT2B and 5-HT2C, among other targets. The reported 5-HT2A binding affinity was approximately 114 nM in that assay. Functional testing also found agonist activity at 5-HT2 receptors, although values differed between receptor subtypes (Receptor binding profiles for tryptamine psychedelics, 2023).
The Swedish assessment had earlier summarised a cell-based study in which 4-HO-MPT acted as a full 5-HT2A agonist, but with substantially lower potency than LSD. The difference between reported potency values illustrates why assay design and receptor expression systems matter when comparing results.
Reported effects
Human descriptions come mainly from older personal accounts and online reports. They mention visual changes, altered colour and sound perception, and changes in mood. These observations are not controlled clinical data. There is no well-established description of the compound’s duration or the frequency of adverse effects.
Clinical evidence and research gaps
No controlled human trial or substantial clinical case series specific to 4-HO-MPT was identified in the available literature. Its metabolism, acute toxic range, dependence potential and long-term effects remain poorly characterised.
The 2023 receptor study adds detail to the previously limited pharmacological evidence, but receptor binding does not establish clinical safety or predict the response in an individual. Findings for 4-HO-MiPT and 4-HO-MET cannot be assumed to apply directly to 4-HO-MPT.
Related tryptamines
4-HO-MPT is related to 4-HO-MiPT, 4-HO-MET, 4-HO-DPT and 4-AcO-MPT. Its N-methyl-N-propyl side chain distinguishes it from the methyl-isopropyl and diethyl analogues.
