4-HO-DPT
4-hydroxy-N,N-dipropyltryptamine
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4-HO-DPT (4-hydroxy-N,N-dipropyltryptamine) is a synthetic psychedelic of the tryptamine class. It is a structural analog of psilocin, with lower potency and a longer duration. It activates serotonin receptors in the brain, disrupting how the brain filters sensory input and producing the visual and cognitive shifts characteristic of classical psychedelics.[1]
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First synthesized in 1977 as part of a psilocin analog series,[2] it was never tested for effects. Shulgin later reported only a faint threshold response at 20 mg,[3] called the synthesis difficult, and moved on — shelving the compound for decades. It appeared on research chemical markets substantially later than most tryptamines and remains one of the least characterized in its class.
Subjective effects include geometric visual patterns, brightened colors, sensory intensification, and altered thinking. The experience is more visually elaborate and less emotionally confrontational than psilocin — sensory-rich rather than introspective, with less of the psychological weight shorter-chain relatives carry. Nausea during onset, anxiety at higher doses, and dysphoric reactions in unsupported settings are common unwanted effects.
4-HO-DPT produces no physical dependence,[4] and no human fatality has been attributed to it. Psychological risk — anxiety, paranoia, and dysphoric reactions — scales with dose and worsens sharply in unsupported settings; monoamine oxidase inhibitors create risk of life-threatening serotonin overload. No controlled human studies have been published; what is known comes almost entirely from user reports and analogy to related compounds.
History[edit]
Discovery
4-HO-DPT was first synthesized in 1977 by David B. Repke, William J. Ferguson, and Dale K. Bates, reported in a paper describing synthetic routes to psilocin analogs.[2] No pharmacological testing was done — the work was purely chemical. Alexander Shulgin later prepared the compound and documented it in TiHKAL (1997),[3] reporting only a possible threshold effect at 20 mg and describing the synthesis as "difficult to make" — effectively discouraging further investigation.
Parent Compound Clinical History
4-HO-DPT itself has no clinical trial history, but its parent compound DPT does. Soskin, Grof, and Richards published a double-blind study in 1973 using intramuscular DPT as a psychotherapy adjunct for alcoholism,[5] with Soskin extending the work in 1975[6] — part of the broader psychedelic therapy movement of the 1950s–1970s.[7]
Modern Status
4-HO-DPT appeared on grey-market research chemical sites substantially later than most comparable tryptamines. Chapman (2017) confirmed the chemical identity of commercially available material by NMR spectroscopy,[8] and Sammeta et al. (2020) published the first crystal structure.[9] It remains one of the least explored compounds in its structural family.
The informal name Procin follows the naming pattern used across 4-hydroxytryptamines: psilocin (DMT), metocin (MET), miprocin (MiPT). The "-cin" suffix signals 4-hydroxy substitution; "pro-" references the propyl chains. Despite the systematic logic, Procin has seen minimal adoption — the compound's limited circulation keeps the alphanumeric designation 4-HO-DPT dominant.
Chemistry[edit]
Structural Class
4-HO-DPT belongs to the 4-hydroxytryptamine family — the same structural group as psilocin (4-HO-DMT). The core is an indole ring with a hydroxyl group at the 4-position — the structural feature shared with psilocin.[10] Two n-propyl chains on the nitrogen distinguish it from psilocin's two methyl groups. It sits in a homologous series — 4-HO-DMT, 4-HO-DET, 4-HO-DPT — where longer nitrogen chains progressively shift receptor preferences.[1]
Molecular Properties
| Molecular formula | C₁₆H₂₄N₂O |
| Molecular weight | 260.37 g/mol |
The freebase melts at 96–97 °C, first established by Repke et al.[2] and confirmed by Shulgin.[3] The compound has no chirality center. The hydrochloride salt has been characterized by X-ray crystallography;[9] the fumarate salt by NMR.[8]
Pharmacology[edit]
Mechanism of Action
4-HO-DPT activates serotonin receptors in the brain — the same system responsible for the psychedelic effects of psilocin and LSD. No binding data specific to 4-HO-DPT have been published. The classification rests on class-level evidence: all tested 4-hydroxy-N,N-dialkyltryptamines activate this receptor system,[1] the parent compound DPT is a confirmed full activator,[11] and the 4-hydroxyl group enhances rather than reduces this activity.[12]
The N,N-dipropyl chains give 4-HO-DPT approximately 129-fold selectivity for the primary psychedelic serotonin receptor compared to psilocin,[10] with increased activity at a third serotonin subtype linked to heart valve damage from chronic stimulation.[1] Psychedelic potency across this class is predicted most reliably by the strength of Gq protein signaling triggered by receptor activation.[4]
Pharmacokinetics
No human pharmacokinetic data exist for 4-HO-DPT. By analogy with psilocin, the 4-hydroxyl group likely undergoes liver metabolism, and the class is generally broken down by MAO-A (MAO-A).inferred The faster onset with insufflation compared to oral administration[10] is consistent with first-pass liver metabolism slowing oral absorption — a pattern seen across the tryptamine class.
Neuroscience[edit]
Where It Acts
No direct brain imaging data exist for 4-HO-DPT. Based on its serotonin receptor activation, the compound is expected to disrupt thalamocortical gating — the brain's mechanism for filtering sensory information before it reaches conscious awareness.[13] The result is a flood of sensory and associative signals reaching cortical areas, producing the perceptual shifts characteristic of psychedelic states.
Serotonergic psychedelics also reduce activity in the default mode network — the brain system underlying self-referential thought. This correlates with the subjective sense of ego softening or dissolution.
Why It Matters
One framework proposes that these compounds relax the brain's high-level assumptions, giving raw sensory input greater influence over conscious experience. The compound's enhanced serotonin receptor selectivity could produce a more perceptually dominated experience than psilocin — but this remains speculative.inferred
Several key questions distinguish 4-HO-DPT from better-characterized relatives. Does its receptor selectivity profile translate to measurably different neural activity compared to psilocin? What explains its longer duration — receptor residence time, slower metabolism, or both?
Subjective Effects[edit]
4-HO-DPT has a strongly sensory character. Visual phenomena are elaborate and prominent — geometry, brightened colors, rippling surfaces — while the emotional and introspective depth that defines psilocin and related compounds is comparatively muted. The experience feels more like perception turned up than a journey inward.
Within its structural family, 4-HO-DPT is lighter in emotional weight than Psilocin and reportedly more visually ornate. Users describe it as less confrontational than psilocin — closer to a perceptual shift than a psychological reckoning. These comparisons rest entirely on user reports rather than any controlled study.
Effect Grid
Full psychedelic experience with clear visual, cognitive, and emotional components. Visual drifting, geometric patterning, color enhancement, and symmetrical texture repetition are characteristic. Internal hallucinations may emerge with eyes closed. Music enhancement is prominent — auditory textures feel richer and more spatially defined.
Emotional enhancement and time alteration are reliable features. Thought acceleration and conceptual thinking shift perception of ordinary ideas. Analysis enhancement and pattern recognition enhancement color the cognitive landscape. Nausea is possible during onset, typically resolving as effects build. Body load includes spontaneous body sensations and possible muscle relaxation.
Set and setting meaningfully shape the experience. The insufflated route (15–25 mg) produces faster onset and a more compressed arc than oral administration (60–90 mg). Users report a sensory-dominant character — more visually elaborate and less emotionally confrontational than psilocin at equivalent intensity.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Geometry · Music enhancement · Tracers · Visual breathing · Visual drifting · Brightness alteration · Environmental patterning · Touch enhancement · Visual diffraction · Visual haze / noise · Visual morphing · After-images · Auditory distortion · Auditory enhancement · Depth perception distortion · Light sensitivity · Peripheral vision distortion · Perspective distortion · Sound sensitivity · Spatial disorientation · Symmetrical texture repetition · Vestibular distortion · Visual melting · Auditory misinterpretation · Peripheral misidentification · Proprioceptive distortion · Synesthesia · Visual acuity enhancement · Visual processing acceleration · Visual magnification · Dreaming enhancement · Olfactory enhancement · Taste enhancement · Flashbacks · External hallucinations · Internal hallucinations · Object transformations · Visual recursion · Object activation · Auditory hallucinations · Environmental orbism / cubism · Perspective hallucinations · Visual scenery slicing
Visual drifting · Brightness alteration · Environmental patterning · Touch enhancement · Visual diffraction · Visual haze / noise · Visual morphing · After-images · Auditory distortion · Auditory enhancement · Depth perception distortion · Light sensitivity · Peripheral vision distortion · Perspective distortion · Sound sensitivity · Spatial disorientation · Symmetrical texture repetition · Vestibular distortion · Visual melting · Auditory misinterpretation · Peripheral misidentification · Proprioceptive distortion · Synesthesia · Visual acuity enhancement · Visual processing acceleration · Visual magnification · Dreaming enhancement · Olfactory enhancement · Taste enhancement · Flashbacks · External hallucinations · Internal hallucinations · Object transformations · Visual recursion · Object activation · Auditory hallucinations · Environmental orbism / cubism · Perspective hallucinations · Visual scenery slicing
Spontaneous body sensations · Appetite suppression · Nausea · Stimulation · Tactile euphoria · Tingling / electric sensations · Wakefulness · Bodily heaviness · Body schema distortion · Dizziness · Excessive sweating · Heart rate perception changes · Insomnia · Laughter fits · Physical fatigue · Restlessness · Vibrations / buzzing · Bodily lightness · Bodily pressures · Breathing alteration · Dry mouth · Muscle relaxation · Muscle tension · Sexual arousal enhancement · Trembling · Bruxism · Headache · Involuntary body movements · Kundalini-like energy · Nystagmus (eye wobbles) · Pain suppression · Sedation · Vasoconstriction · Vomiting · Yawning · Diarrhea · Bodily dissociation · Tactile hallucination
Stimulation · Tactile euphoria · Tingling / electric sensations · Wakefulness · Bodily heaviness · Body schema distortion · Dizziness · Excessive sweating · Heart rate perception changes · Insomnia · Laughter fits · Physical fatigue · Restlessness · Vibrations / buzzing · Bodily lightness · Bodily pressures · Breathing alteration · Dry mouth · Muscle relaxation · Muscle tension · Sexual arousal enhancement · Trembling · Bruxism · Headache · Involuntary body movements · Kundalini-like energy · Nystagmus (eye wobbles) · Pain suppression · Sedation · Vomiting · Yawning · Diarrhea · Bodily dissociation · Tactile hallucination
Immersion enhancement · Introspection enhancement · Novelty enhancement · Openness enhancement · Pattern recognition enhancement · Thought connectivity · Cognitive euphoria · Cognitive impairment · Focus suppression · Increased nature relatedness · Multiple thought streams · Thought acceleration · Thought disorganization · Creativity enhancement · Confusion · Humor enhancement · Information processing suppression · Memory fragmentation · Memory suppression · Synchronicity · Thought loops · Analysis enhancement · Analysis suppression · Cognitive dysphoria · Cognitive fatigue · Memory replays · Motivation suppression · Information processing enhancement · Focus enhancement · Language enhancement · Amnesia
Openness enhancement · Pattern recognition enhancement · Thought connectivity · Cognitive euphoria · Cognitive impairment · Focus suppression · Increased nature relatedness · Multiple thought streams · Thought acceleration · Thought disorganization · Creativity enhancement · Confusion · Humor enhancement · Information processing suppression · Memory fragmentation · Memory suppression · Synchronicity · Thought loops · Analysis enhancement · Analysis suppression · Cognitive dysphoria · Cognitive fatigue · Memory replays · Motivation suppression · Information processing enhancement · Focus enhancement · Language enhancement
Catharsis · Empathy enhancement · Anxiety · Dysphoria
Depersonalization · Trust enhancement · Automaticity · Communication suppression · Disinhibition · Flow state · Sociability enhancement · Compulsive behavior reduction · Ego inflation · Social disconnection · Communication enhancement · Boundary dissolution · Ego dissolution · Identity alteration · Cognitive disconnection · Telepathic feelings
Disinhibition · Flow state · Sociability enhancement · Compulsive behavior reduction · Ego inflation · Social disconnection · Communication enhancement · Boundary dissolution · Ego dissolution · Identity alteration · Cognitive disconnection · Telepathic feelings
Time cessation
Transpersonal visions · Death-rebirth sequence · Entity contact · Transpersonal memory access · Near-death experience · Voidness · Cessation
Near-death experience · Voidness · Cessation
Lucidity enhancement · Recursive awareness
Timeline
Subtle alerting and first body awareness. Mild nausea may appear. Mood shifts slightly but no definitive psychedelic effects.
Progressive build of perceptual and cognitive effects. Body load peaks during this phase — nausea is most likely here. Color enhancement and visual acuity changes emerge.
Full expression of visual, cognitive, and emotional effects. Geometry, visual drifting, and music enhancement are prominent. Time alteration and thought acceleration characterize the cognitive state.
Gradual return toward baseline. Residual visual effects (tracers, color shifts) persist while emotional processing continues. Cognitive clarity begins to return.
Mild residual mood elevation and sensory sensitivity. Subtle body awareness may persist.
⚠ Avoid driving or operating heavy machinery for at least 8 hours after oral ingestion.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Low
- Withdrawal
- None
- Tolerance buildup
- rapid
- Tolerance reset
- 7 days
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- psilocin · LSD · mesc
Toxicity
No lethal dose data exist for 4-HO-DPT in any species, and no case reports of fatal or non-fatal overdose have been published.[10] No organ toxicity data exist for this compound.
Seizure Risk
The parent compound DPT produced seizure-like effects in mice at doses above 20 mg/kg.[11] Human oral doses fall far below this threshold, but the finding represents a dose-dependent safety signal for the compound class at very high exposures.safety citation needed
Heart and Circulation
Tryptamines with bulkier nitrogen substituents — including N,N-dipropyl compounds — show increased activity at a serotonin receptor subtype linked to heart valve damage with chronic stimulation.[1] No clinical heart data exist for 4-HO-DPT; the risk is theoretical and most relevant to frequent repeated use.safety citation needed
Reviews of novel tryptamine cases have documented fatalities predominantly linked to multiple-drug use, heart events, and dangerously elevated body temperature[15] — none specific to 4-HO-DPT. Tryptamine-associated health problems are "considerable and underestimated".[16]
Psychological Risks
4-HO-DPT can produce acute anxiety, panic, paranoia, and dysphoric reactions — particularly at high doses, in unsupported settings, or in people with pre-existing psychiatric vulnerability.
Persistent perceptual disturbances after psychedelic use have not been characterized for 4-HO-DPT.citation needed The condition appears rare across the serotonergic psychedelic class but can persist when it occurs. Triggering or worsening psychotic episodes is a class-level risk for all compounds that activate this serotonin receptor system, particularly in people with personal or family history of psychosis.
Tolerance and Dependence
Tolerance develops rapidly — effectively after a single dose — through serotonin downregulation.[4] Community consensus estimates a half-life of approximately 3 days and full reset within 7 days.
Daily DPT in mice did not produce tolerance to psychedelic-indicative responses, unlike phenethylamine hallucinogens.[14] 4-HO-DPT cross-tolerates with all classical serotonergic psychedelics (LSD, psilocin, mescaline, DMT) via shared receptor mechanisms. Serotonergic psychedelics are not habit-forming, and DPT did not produce compulsive redosing in clinical settings.[5]
Drug Interactions
Tramadol — Dangerous
Tramadol blocks serotonin reuptake[17] and lowers the seizure threshold. Combined with a serotonergic tryptamine that also raises serotonin levels,[18] this creates dual risk: serotonin syndrome and seizures.[11]
MAO Inhibitors — Dangerous
MAO-A is the primary enzyme that breaks down tryptamines. Blocking it dramatically elevates 4-HO-DPT blood levels and extends duration, and the combined serotonin-raising effects can produce life-threatening serotonin toxicity.[18]safety citation needed
Cannabis — Unknown
THC interacts with serotonin signaling through cannabinoid receptor mechanisms. Cannabis may intensify or alter the experience, potentially increasing anxiety. No controlled data exist for this combination with 4-HO-DPT.
Lithium — Caution
Lithium combined with serotonergic psychedelics is associated with increased seizure risk in published case reports and is recognized as a contraindication in standard psychedelic harm reduction guidelines.safety citation needed
SSRIs and SNRIs
Serotonin reuptake inhibitors may weaken or unpredictably alter psychedelic effects while introducing theoretical serotonin toxicity risk, particularly at high doses.citation needed
Contraindications
Absolute contraindications:
- MAO inhibitors: Life-threatening serotonin toxicity — blocking the primary pathway that breaks down tryptamines
- Lithium: Increased seizure risk; replicated across case reports involving psilocybin and LSD
Relative contraindications:
- Personal or family history of psychotic spectrum disorders: Serotonin receptor activation can trigger or worsen psychotic episodes
- Heart conditions: Theoretical valve damage risk with repeated exposure; possible acute cardiovascular effectssafety citation needed
- Tramadol or other serotonergic medications: Serotonin syndrome risk and seizure threshold reduction
- Pregnancy: No safety data; effects during development are unexploredcitation needed
Harm Reduction[edit]
Forms & Identification
4-HO-DPT circulates primarily as powder in freebase, hydrochloride, or fumarate salt forms. Reagent testing confirms the presence of an indole-class compound but cannot definitively identify 4-HO-DPT. Exact identity requires laboratory analysis or cross-referencing multiple reagent results against known reaction profiles.
Salt form matters for dosing. A milligram of fumarate salt contains less active compound than a milligram of freebase due to the added mass of the salt counterion. Switching between salt forms means doses are not directly interchangeable.
Guidelines
- Test all material with reagent kits before use. Laboratory analysis provides definitive identification where available.
- Start with a low dose to establish individual sensitivity — dosing data for this compound are sparse.
- Use a milligram-precision scale (0.001 g). Volumetric dosing in solution improves accuracy for small quantities.
- Avoid redosing during the experience. Tolerance onset is rapid and unpredictable dose stacking can produce overwhelming effects.
- Ensure a sober, trusted person is present, especially for first experiences.
- Eat lightly several hours before to reduce nausea during onset.
- Clear the schedule for the full duration plus several hours of recovery. Do not drive or operate machinery.
- Keep the environment comfortable, warm, and controllable — the ability to adjust music, lighting, and surroundings matters.
Set & Setting
The quality of a 4-HO-DPT experience is heavily shaped by mindset and environment. Anxiety, unresolved stress, or unfamiliar surroundings increase the likelihood of a difficult experience. A calm, private space with a trusted sober person present — particularly for first experiences or higher doses — substantially reduces psychological risk.
The compound's limited characterization means fewer people have experience supporting others through its effects. A sitter familiar with psychedelic states in general is preferable to navigating a first experience alone.
Aftercare & integration. The days following a 4-HO-DPT experience may include emotional sensitivity, fatigue, and residual shifts in perception. These typically resolve within 24–48 hours.
Journaling or discussing the experience while memories are fresh can help process unusual or challenging content. For experiences involving difficult emotions, ego dissolution, or disorientation, professional integration support from a therapist familiar with psychedelic experiences is valuable. Allow at least 7 days before another psychedelic experience to permit full tolerance reset and emotional processing.
Recovery & Support
Serotonergic psychedelics carry low abuse liability, and compulsive use patterns are rare. If psychedelic use is becoming a way to avoid addressing problems rather than a tool for insight, that pattern is worth examining honestly.
For those experiencing persistent distress, HPPD symptoms, or difficulty reintegrating after psychedelic experiences, professional support is available. The Fireside Project (62-FIRESIDE / 623-473-7433) offers free peer support for psychedelic experiences. MAPS maintains a directory of integration-aware therapists.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency:
Most difficult psychedelic experiences are distressing but not medically dangerous. Seek immediate help if any of the following occur:
- Loss of contact with reality combined with self-harm risk or dangerous behavior
- Seizures or convulsions
- Chest pain or irregular heartbeat
- Severe uncontrollable overheating (skin hot to touch, confusion)
- Loss of consciousness
Immediate steps:
- 1. Stay with the person. Speak calmly and simply.
- 2. Call emergency services if the person is physically endangering themselves, having seizures, or is unresponsive.
- 3. Move them to a quiet, safe space. Reduce stimulation — dim lights, lower noise.
- 4. Do not restrain them unless there is immediate danger to themselves or others.
- 5. If unconscious, place in the recovery position and monitor breathing.
What to tell the dispatcher:
State the substance name (4-HO-DPT, a synthetic tryptamine), approximate amount and time taken, current symptoms, and the person's age and weight. Good Samaritan laws in many jurisdictions protect people who call for help during drug emergencies.
Legal Status[edit]
4-HO-DPT is not explicitly scheduled under most national drug laws, but broad structural analog provisions and novel psychoactive substance legislation may apply depending on jurisdiction.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Not explicitly scheduled | Not listed in CSA Schedules I–V. The Federal Analogue Act (21 U.S.C. § 813) may apply if intended for human consumption, given structural similarity to psilocin (Schedule I). DEA proposed scheduling of 4-OH-DiPT (a different compound) and later withdrew it.[19] |
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Controlled under the tryptamine catch-all clause. Possession and supply are criminal offenses. The Psychoactive Substances Act 2016 also applies. |
| Germany | Controlled (NpSG) | Covered under the Neue-psychoaktive-Stoffe-Gesetz since July 2019. Possession for personal use not criminalized; supply and trade prohibited. |
| Canada | Not scheduled | Not listed in Schedules I–VI of the Controlled Drugs and Substances Act. No analog provision equivalent to the US Federal Analogue Act. |
| Switzerland | Possibly uncontrolled | Not listed under controlled substance categories A–D. Status uncertain; subject to regulatory change. |
| Australia | Status unconfirmed | Several tryptamines are Schedule 9 (Prohibited Substances). Whether 4-HO-DPT falls under existing scheduling entries could not be confirmed.citation needed |
Legal status changes frequently and varies by jurisdiction. This information reflects available data at time of writing and may be out of date. Nothing here constitutes legal advice.
Analog Act Considerations
4-HO-DPT differs from psilocin (4-HO-DMT) only in the length of the nitrogen-attached alkyl chains. Under the US Federal Analogue Act, a substance substantially similar in structure or pharmacological effect to a Schedule I substance may be treated as controlled if intended for human consumption. This creates legal risk for possession or distribution of 4-HO-DPT despite the absence of explicit scheduling.
references
- [1]
- [2] ^abcRepke D, Ferguson W, Bates D (1977) Psilocin analogs. 1. Synthesis of 3-[2-(dialkylamino)ethyl]-and 3-[2-(cycloalkylamino)ethyl] indol-4-ols — Journal of Heterocyclic Chemistry doi:10.1002/jhet.5570140113
- [3]
- [4] ^abcWallach J, Cao AB, Calkins MM, Heim AJ, Lanham JK, et al. (2023) Identification of 5-HT2A receptor signaling pathways associated with psychedelic potential — Nature Communications doi:10.1038/s41467-023-44016-1
- [5] ^abSoskin RA, Grof S, Richards WA (1973) Low doses of Dipropyltryptamine in psychotherapy. — Archives of general psychiatry PMID:4575167
- [6]