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Summary sheet: Diphenidine
Chemical Nomenclature
Common names Diphenidine
Systematic name (±)-1-(1,2-Diphenylethyl)piperidine
Class Membership
Psychoactive class Dissociative
Chemical class Diarylethylamine
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold Common Heavy
50 - 70 - 85 - 110 - 150 mg
Light Strong
Threshold 50 - 70 mg
Light 70 - 85 mg
Common 85 - 110 mg
Strong 110 - 150 mg
Heavy > 150 mg
Total 2 - 5 hours
Onset 15 - 30 minutes
After effects 4 - 24 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.

Diphenidine is a lesser-known novel dissociative substance of the diarylethylamine class that produces dissociative and hallucinogenic effects when administered. It is structurally related to methoxphenidine and ephenidine.

The synthesis of diphenidine was first reported in 1924. Shortly after the 2013 UK arylcyclohexylamine ban, diphenidine and the related compound methoxphenidine became available on the grey market. In 2014, there were two cases of diphenidine being sold in combination with synthetic cannabinoids in Japanese herbal incense blends, one of which was implicated in a fatal overdose.

Diphenidine is classified as an NMDA receptor antagonist.[1] Members of this class induce a state known as "dissociative anesthesia" and are used in both medical and recreational contexts. These include arylcyclohexylamines like ketamine and phencyclidine (PCP), as well as dextromethorphan (DXM).

Anecdotal reports describe high doses of diphenidine producing "bizarre somatosensory phenomena and transient anterograde amnesia."[2]

Very little data exists about the pharmacological properties, metabolism, and toxicity of diphenidine in humans, and it has an extremely limited history of human usage. Many reports suggest that it may pose different risks than traditional dissociatives. It is highly advised to use harm reduction practices if using this substance.

History and culture

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The synthesis of diphenidine was first reported in 1924. It employed a nitrile displacement reaction analogous to the one that would later be used to discover phencyclidine in 1956. Shortly after the 2013 UK ban on arylcyclohexylamines, diphenidine and the related compound methoxphenidine became available on the grey market.

In 2014, there were two cases of diphenidine being sold in combination with synthetic cannabinoids in Japanese herbal incense blends. One herbal incense blend was found to contain diphenidine and 5-fluoro-AB-PINACA at concentrations of 289 mg/g and 55.5 mg/g, respectively.[3] Another product containing AB-CHMINACA, 5F-AMB, and diphenidine was implicated in a fatal overdose.[4]


Generic structure of a piperdine molecule.

Diphenidine is a molecule of the diarylethylamine class. It contains a substituted phenethylamine skeleton with an additional phenyl ring bound to Rα. The terminal amino group of the phenethylamine chain is incorporated into a piperidine ring. Hence, diphenidine belongs to the piperidine dissociative class of compounds. Diphenidine is structurally analogous to MXP, lacking a 2-methoxy substitution on one of its phenyl rings.


Further information: NMDA receptor antagonist

Diphenidine acts as an NMDA receptor antagonist.[5][6] NMDA receptors allow for electrical signals to pass between neurons in the brain and spinal column; for the signals to pass, the receptor must be open. Dissociatives close the NMDA receptors by blocking them. This disconnection of neurons leads to loss of feeling, difficulty moving, and eventually the famous “hole”.

Although vendors of diphenidine have stated the compound acts as a dopamine-reuptake inhibitor and a serotonin reuptake inhibitor with µ-opioid affinity and typical dissociative effects, to date diphenidine has not been screened for affinity at the dopamine transporter. If this is indeed the case, however, it provides an explanation for its euphoric and often stimulating effects.

Diphenidine and related diarylethylamines have been studied in vitro as treatments for neurotoxic injury.[7] Diphenidine may be a stronger NMDA receptor antagonist for neurogenesis, neurological repair and neuroprotection than other more common NMDA receptor antagonistic dissociatives such as ketamine, dextromethorphan, PCP analogs, Iboga and methoxetamine.

Subjective effects

The general head space of diphenidine is often described as euphoric and clear-headed in comparison to that of ketamine and reminiscent of ephenidine at lower dosages. Moderate or higher dosages can sometimes unwillingly turn very confusing and dysphoric without any apparent cause.

Diphenidine is reported to have a much more rapid onset and lower half-life when vaporized or smoked. When consumed this way, it is a suspected to be carcinogenic when excess heat is used. Some user reports have concluded that vaporization requires as low as 20% of what would be a common oral dose for that person.

The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWiki contributors. These effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances of inducing a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.

Physical effects

Visual effects

Cognitive effects

Disconnective effects

Experience reports

Anecdotal reports which describe the effects of this compound within our experience index include:

Additional experience reports can be found here:

Toxicity and harm potential

The toxicity and long-term health effects of recreational diphenidine use do not seem to have been studied in any scientific context and the exact toxic dosage is unknown. This is because diphenidine has very little history of human usage.

Anecdotal evidence from those who have tried diphenidine suggest that there do not seem to be any negative health effects attributed to simply trying this drug at low to moderate doses by itself and using it sparingly (but nothing can be completely guaranteed). Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

It is strongly recommended that one use harm reduction practices when using this substance.

Tolerance and addiction potential

As with other NMDA receptor antagonists, the chronic use of diphenidine can be considered moderately addictive with a high potential for abuse and is capable of causing psychological dependence among certain users. When addiction has developed, cravings and withdrawal effects may occur if a person suddenly stops their usage.

Tolerance to many of the effects of diphenidine develops with prolonged and repeated use. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). Diphenidine presents cross-tolerance with all dissociatives, meaning that after the consumption of diphenidine all dissociatives will have a reduced effect.

Dangerous interactions

Although many psychoactive substances are safe to use on their own, they can become dangerous or even life-threatening when taken with other substances. The list below contains some potentially dangerous combinations, but may not include all of them. Certain combinations may be safe in low doses but still increase the possibility of injury of death. Independent research should always be conducted to ensure that a combination of two or more substances is safe before consumption.

  • Stimulants - Both stimulants and dissociatives carry the risk of adverse psychological reactions like anxiety, mania, delusions and psychosis and these risks are exacerbated when the two substances are combined.
  • Depressants - Because both depress the respiratory system, this combination can result in an increased risk of suddenly falling unconscious, vomiting and choking to death from the resulting suffocation. If nausea or vomiting occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.

Legal status

Diphenidine is currently a legal grey area drug worldwide and is easily accessible through the use of online research chemical vendors. However, this does not guarantee anyone to be immune from legal prosecution should they be found in possession of this substance as the legality is likely to vary from country to country.

  • Canada: As of March 2016, MT-45 and its analogues, one of which being Diphenidine, are Schedule I controlled substances.[8] Possession without legal authority can result in maximum 7 years imprisonment. Only those with a law enforcement agency, person with an exemption permit or institutions with Minister's authorization may possess the drug.
  • United Kingdom: It is illegal to produce, supply, or import this drug under the Psychoactive Substance Act, which came into effect on May 26th, 2016.[9]

See also

External links



  • Wallach, J., Kang, H., Colestock, T., Morris, H., Bortolotto, Z. A., Collingridge, G. L., ... & Adejare, A. (2016). Pharmacological investigations of the dissociative ‘legal highs’ diphenidine, methoxphenidine and analogues. PLoS One, 11(6), e0157021. https://doi.org/10.1371/journal.pone.0157021
  • Morris, H., & Wallach, J. (2014). From PCP to MXE: A comprehensive review of the non-medical use of dissociative drugs. Drug Testing and Analysis, 6(7–8), 614–632. https://doi.org/10.1002/dta.1620


  1. Wallach, J., Kang, H., Colestock, T., Morris, H., Bortolotto, Z. A., Collingridge, G. L., ... & Adejare, A. (2016). Pharmacological investigations of the dissociative ‘legal highs’ diphenidine, methoxphenidine and analogues. PLoS One, 11(6), e0157021. https://doi.org/10.1371/journal.pone.0157021
  2. From PCP to MXE: a comprehensive review of the non-medical use of dissociative drugs | http://onlinelibrary.wiley.com/doi/10.1002/dta.1620/abstract;jsessionid=C8EDD090D25084ED0088835B767DD0B9.f04t02
  3. http://link.springer.com/article/10.1007%2Fs11419-014-0240-y | http://worldwide.espacenet.com/publicationDetails/biblio?CC=EP&NR=0346791&KC=&FT=E&locale=en_EP
  4. Postmortem distribution of AB-CHMINACA, 5-fluoro-AMB, and diphenidine in body fluids and solid tissues in a fatal poisoning case: usefulness of adipose tissue for detection of the drugs in unchanged forms | http://link.springer.com/article/10.1007%2Fs11419-014-0245-6
  5. NMDA receptor affinities of 1,2-diphenylethylamine and 1-(1,2-diphenylethyl)piperidine enantiomers and of related compounds (ScienceDirect) | http://www.sciencedirect.com/science/article/pii/S0968089609002624
  6. Preparation and characterization of the ‘research chemical’ diphenidine, its pyrrolidine analogue, and their 2,2-diphenylethyl isomers | http://onlinelibrary.wiley.com/doi/10.1002/dta.1689/abstract
  7. 1,2-diarylethylamines for treatment of neurotoxic injury | http://worldwide.espacenet.com/publicationDetails/biblio?CC=EP&NR=0346791&KC=&FT=E&locale=en_EP
  8. Regulations Amending the Food and Drug Regulations (Parts G and J — Lefetamine, AH-7921, MT-45 and W-18) | http://www.gazette.gc.ca/rp-pr/p2/2016/2016-06-01/html/sor-dors106-eng.php
  9. Psychoactive Substances Act 2016 (Legislation.gov.uk) | http://www.legislation.gov.uk/ukpga/2016/2/contents/enacted