Diphenidine (1,2-DEP, DPD, DND) is a dissociativeanesthetic that has been sold as a designer drug.[2][3][4] The synthesis of diphenidine was first reported in 1924, and employed a Bruylants reaction analogous to the one that would later be used to discover phencyclidine in 1956.[2] Shortly after the 2013 UK ban on arylcyclohexylamines, diphenidine and the related compound methoxphenidine became available on the grey market.[2] Anecdotal reports describe high doses of diphenidine producing "bizarre somatosensory phenomena and transient anterograde amnesia."[2] Diphenidine and related diarylethylamines have been studied in vitro as treatments for neurotoxic injury and are antagonists of the NMDA receptor.[5][6][7][8][9] In dogs diphenidine exhibits greater antitussive potency than codeine phosphate.[10][11]
Electrophysiological analysis demonstrates that the amplitude of NMDA-mediated fEPSPs are reduced by diphenidine and ketamine to a similar extent, with diphenidine displaying a slower onset of antagonism.[7] The two enantiomers of diphenidine differ greatly in their ability to block the NMDA receptor, with the more potent (S)-enantiomer possessing affinity forty times higher than the (R)-enantiomer.[6] Since diphenidine's introduction in 2013 vendors have stated the drug "acts on dopamine transport" yet no data concerning the action of diphenidine on the dopamine transporter was published until 2016.[2] Diphenidine's highest affinity is for the NMDA receptor, but it does display submicromolar affinity for the σ1 receptor, σ2 receptor and dopamine transporter.[12][13]
Since 2014 there have been several published reports of diphenidine being sold in combination with other research chemicals, particularly synthetic cannabinoids and stimulants in Japanese herbal incense blends.[14][15][16] The first reported seizure concerned a Japanese product called "fragrance powder" containing diphenidine and benzylpiperazine.[17] A herbal incense sold in the Shizuoka Prefecture under the name "Aladdin Spacial [sic] Edition" was found to contain diphenidine and 5F-AB-PINACA at concentrations of 289 mg/g and 55.5 mg/g, respectively.[14] A product called Herbal Incense. The Super Lemon containing AB-CHMINACA, 5F-AMB, and diphenidine was implicated in a fatal poisoning.[15] Most recently diphenidine consumed in conjunction with three substituted cathinones, three benzodiazepines, and alcohol was implicated in a fatal ingestion of "bath salt" and "liquid aroma" products in Japan.[18]
In Canada, MT-45 and its analogues were made Schedule I controlled substances, which includes DPD in its structural group.[19] Possession without legal authority can result in maximum seven years imprisonment. Further, Health Canada amended the Food and Drug Regulations in May, 2016 to classify explicitly DPD as a restricted drug. Only those with a law enforcement agency, person with an exemption permit or institutions with Minister's authorization may possess the drug.
^ abcdeMorris H, Wallach J (July–August 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. doi:10.1002/dta.1620. PMID24678061.
^Wink CS, Michely JA, Jacobsen-Bauer A, Zapp J, Maurer HH (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. doi:10.1002/dta.1946. PMID26811026.
^Helander A, Beck O, Bäckberg M (June 2015). "Intoxications by the dissociative new psychoactive substances diphenidine and methoxphenidine". Clinical Toxicology. 53 (5): 446–453. doi:10.3109/15563650.2015.1033630. PMID25881797. S2CID5962038.
^EP 0346791, Gray NM, Cheng BK, "1,2-diarylethylamines for treatment of neurotoxic injury", issued 6 April 1994, assigned to G.D. Searle, LLC
^ abBerger ML, Schweifer A, Rebernik P, Hammerschmidt F (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. doi:10.1016/j.bmc.2009.03.025. PMID19345586.
^Rogawski MA (September 1993). "Therapeutic potential of excitatory amino acid antagonists: channel blockers and 2,3-benzodiazepines". Trends in Pharmacological Sciences. 14 (9): 325–331. doi:10.1016/0165-6147(93)90005-5. PMID7504360.
^Kase Y, Yuizono T, Muto M (March 1963). "Piperidino Groups in Antitussive". Journal of Medicinal Chemistry. 6 (2): 118–122. doi:10.1021/jm00338a007. PMID14188779.
^Cahusac PM, Senok SS, Hitchcock IS, Genever PG, Baumann KI (May 2005). "Are unconventional NMDA receptors involved in slowly adapting type I mechanoreceptor responses?". Neuroscience. 133 (3): 763–773. doi:10.1016/j.neuroscience.2005.03.018. PMID15908129. S2CID15610561.
^ abWurita A, Hasegawa K, Minakata K, Watanabe K, Suzuki O (August 2014). "A large amount of new designer drug diphenidine coexisting with a synthetic cannabinoid 5-fluoro-AB-PINACA found in a dubious herbal product". Forensic Toxicology. 32 (2): 331–337. doi:10.1007/s11419-014-0240-y. S2CID25995354.
^ abHasegawa K, Wurita A, Minakata K, Gonmori K, Nozawa H, Yamagishi I, Watanabe K, Suzuki O (January 2015). "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". Forensic Toxicology. 33 (1): 45–53. doi:10.1007/s11419-014-0245-6. S2CID11884184.
^Minakata K, Yamagishi I, Nozawa H, Hasegawa K, Wurita A, Gonmori K, Suzuki M, Watanabe K, Suzuki O (July 2015). "Diphenidine and its metabolites in blood and urine analyzed by MALDI-Q-TOF mass spectrometry". Forensic Toxicology. 33 (2): 402–408. doi:10.1007/s11419-015-0273-x. S2CID44007379.
^Kudo K, Usumoto Y, Kikura-Hanajiri R, Sameshima N, Tsuji A, Ikeda N (September 2015). "A fatal case of poisoning related to new cathinone designer drugs, 4-methoxy PV8, PV9, and 4-methoxy PV9, and a dissociative agent, diphenidine". Legal Medicine. 17 (5): 421–426. doi:10.1016/j.legalmed.2015.06.005. PMID26162997.