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Diphenidine

Diphenidine molecule structureDiphenidine molecule structure
Diphenidine
DPD, DND, 1,2-DEP
Psychoactive Class
DissociativeHallucinogen
Chemical Class
Diarylethylamine (substituted)

Diphenidine is a dissociative anesthetic of the diarylethylamine class that acts as an NMDA receptor antagonist.citation needed First synthesized in 1924, it emerged on the grey market following the 2013 UK ban on arylcyclohexylamines. Its structure closely resembles that of MK-801 (dizocilpine). High doses have been associated with bizarre somatosensory phenomena and transient anterograde amnesia. The dose-response curve is reported to be particularly steep, warranting careful attention to dosing.

Dosage & Duration

Dosage

Doses are population estimates that vary widely between individuals.

Threshold~50 mg
Light50-85 mg
Moderate85-110 mg
Strong110-150 mg
Heavy150+ mg

Limited human data exists for this substance, making cautious dose titration particularly important.

Duration

Onset15-30 minutes
After Effects4-24 hours
Total2-5 hours

Subjective Effects

Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.

Effects vary widely by individual, dose, and context.

Physical

Tactile disconnectionPhysical autonomy

Cognitive

The general head space of diphenidine is often described as particularly euphoric and clear headed in comparison to that of DXM and ketamine.

Consciousness disconnectionEgo suppression, loss and deathThought decelerationInformation processing suppressionTime distortionCognitive euphoriaIntrospectionDéjà vuConceptual thinkingCompulsive redosing

Visual

This substance does not enhance visual stimuli; instead it tends to degrade and decrease visual aptitude in a variety of ways.

Distortions

Geometry

The visual geometry of diphenidine can be described as very dark and bland when compared to that of ketamine or DXM and often consists of many tiny interlocking and woven lines. It does not extend beyond level 4 and can be comprehensively described as simplistic in complexity, algorithmic in style, synthetic in feel, unstructured in organization, dimly lit in lighting, multicoloured in scheme, glossy in shading, soft in edges, small in size, slow in speed, smooth in motion, equal in rounded and angular corners, immersive in depth and consistent in intensity.

Hallucinatory States

At high dosages, diphenidine can produce a full range of high level hallucinatory states in a fashion that is less consistent and reproducible than that of many other commonly used psychedelics.

Suppressions

Visual acuity suppression

Auditory

EnhancementsSuppressionDistortionsHallucinations
Forked from Subjective Effect Documentation byJosie Kins January 2015.

See also: Dissociative Intensity Scale, Subjective Effects of Dissociatives

Reagent Testing

Expected colorimetric results for common reagent tests. Colors show reaction change over 1–2 minutes.

Marquis(MQ)
white → orange2 → red2
Mecke(ME)
white → yellow2
Mandelin(MD)
yellow2 → green1
Liebermann(LB)
white → orange2 → red2
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Pharmacology

Pharmacodynamics

Diphenidine acts primarily as an NMDA receptor channel blocker, reducing the amplitude of NMDA-mediated field excitatory postsynaptic potentials to a degree comparable to ketamine, though with a slower onset of antagonism.citation needed The compound's enantiomers differ markedly in potency at this target, with the (S)-enantiomer approximately 40 times more potent than the (R)-enantiomer.1 Beyond the NMDA receptor, diphenidine binds with submicromolar affinity to σ1 and σ2 receptors as well as the dopamine transporter.2

Pharmacokinetics

Diphenidine metabolism has been investigated in rat urine and in pooled human liver preparations. The study identified mono- and bis-hydroxylation and dehydrogenated or oxo products in the human preparations; rat data additionally supported N,N-bis-dealkylation, glucuronidation, and methylation pathways.34 In the in vitro enzyme experiments, CYP1A2, CYP2B6, CYP2C9, and CYP3A4 formed the three initial hydroxylated metabolite classes, while CYP2D6 formed two of them. Two monohydroxylated metabolites were also reported in blood and urine from a fatal case involving diphenidine.4 These findings establish metabolic pathways, but they do not establish diphenidine's clinical human bioavailability, clearance, elimination half-life, or the relative abundance of its metabolites in living people.34

Metabolitesnone documented yet

Interactions

Interactions not written up yet

An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.

Check TripSit

Tolerance

Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.

Full Tolerance
A very strong tolerance develops with diphenidine use, resulting in the need to consume increasingly large doses to achieve the same level of effects.
Cross Tolerance

Dissociatives, NMDA receptor antagonists

Baseline Reset
After 1-2 weeks without use, tolerance is expected to return to baseline.

Harm Potential

Addiction & Dependence

Psychological

Low

Classified as habit-forming with compulsive redosing reported as a notable cognitive effect. Addictive potential remains poorly characterized due to limited research, though anecdotal evidence suggests it should not be binged.citation needed

History & Culture

Diphenidine was originally synthesized in 1924 through a Bruylants reaction, a nitrile displacement method that would later prove instrumental in the discovery of phencyclidine over three decades later in 1956.citation needed Despite this early synthesis, the compound remained largely obscure for…

Trip Reports

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Legality

By Country

Not scheduled1
United Kingdom flagUnited KingdomGrey market (historical, circa 2013-2015)

References

Source Pages

  1. 1,2-Diarylethylamine NMDA Affinity Table
  2. Bluelight: The Big & Dandy Diphenidine Thread
  3. Disregard Everything I Say
  4. Drug Users Bible by Dominic Milton Trott
  5. Erowid: Diphenidine Experience Vaults
  6. PsychonautWiki: Diphenidine
  7. Wikipedia

Citations

  1. Michael L. Berger, Anna Schweifer, Patrick Rebernik, & Friedrich Hammerschmidt. (May 2009). NMDA receptor affinities of 1,2-diphenylethylamine and 1-(1,2-diphenylethyl)piperidine enantiomers and of related compounds. Bioorganic & Medicinal Chemistry, 17(9), 3456–3462. https://doi.org/10.1016/j.bmc.2009.03.0251
  2. Jason Wallach, Heather Kang, Tristan Colestock, Hamilton Morris, Zuner A. Bortolotto, Graham L. Collingridge, David Lodge, Adam L. Halberstadt, Simon D. Brandt, & Adeboye Adejare. (17 June 2016). Pharmacological Investigations of the Dissociative 'Legal Highs' Diphenidine, Methoxphenidine and Analogues. PLOS ONE, 11(6). https://doi.org/10.1371/journal.pone.0157021123
  3. Carina S. D. Wink, Julian A. Michely, Andrea Jacobsen‐Bauer, Josef Zapp, & Hans H. Maurer. (October 2016). Diphenidine, a new psychoactive substance: metabolic fate elucidated with rat urine and human liver preparations and detectability in urine using GC‐MS, LC‐MSn, and LC‐HR‐MSn. Drug Testing and Analysis, 8(10), 1005–1014. https://doi.org/10.1002/dta.194612
  4. World Health Organization. (2020). Critical Review Report: Diphenidine — Expert Committee on Drug Dependence, 43rd Meeting. World Health Organization. https://cdn.who.int/media/docs/default-source/controlled-substances/43rd-ecdd/diphenidine-report-complete.pdf123
  5. The Misuse of Drugs Act 1971 (Amendment) Order 2013. (2013). https://www.legislation.gov.uk/uksi/2013/239/made1

Further Reading

  1. ACMD Review of Evidence on Diphenidine (UK, 2023)
  2. Case of Non-Fatal Intoxication with Diphenidine (2017)
  3. Deaths Related to Diarylethylamines - Journal of Psychopharmacology 2025
  4. European Monitoring Centre - NPS Report on Dissociatives 2024
  5. Pharmacological Investigations of Dissociative ‘Legal Highs’ – PLOS ONE 2016
  6. Preparation and Characterization of Diphenidine Analogs – Drug Testing & Analysis 2015
  7. UNODC: Early Warning Advisory - Diphenidine Profile

Article Status

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