Drug testing and analysis
January 1, 2014
Hamilton Morris, Jason Wallach
240 citations
More than 30 dissociative compounds have been used non-medically over the past 60 years, starting with PCP in the 1950s and later including ketamine and dextromethorphan. At least 14 PCP derivatives were sold illicitly from the 1960s to the 1990s. The Internet transformed the drug market, shifting from gray-market vendors to online research chemical suppliers. The first dissociative research chemical, 4-MeO-PCP, appeared in 2008, and the market now includes at least 12 dissociatives, nearly half previously unknown in scientific literature. Methoxetamine achieved widespread international use. This historical account presents the first complete portrait of the underground dissociative market, alongside legal, technological, and scientific developments driving its evolution.
Nat Commun
December 15, 2023
Jason Wallach, Andrew B. Cao, Maggie M. Calkins et al.
153 citations
Serotonergic psychedelics show therapeutic potential, but the specific roles of 5-HT2A receptor signaling pathways are unclear. Researchers developed selective ligands with varying Gq efficacies, including β-arrestin-biased ones. In male mice, 5-HT2A-Gq recruitment efficacy, not β-arrestin2 recruitment, predicted psychedelic potential measured by head-twitch response magnitude. Disrupting Gq-PLC signaling reduced this response, and a threshold Gq activation level was needed for psychedelic-like effects, explaining why partial agonists like lisuride are non-psychedelic. β-arrestin-biased agonists blocked psychedelic effects and caused receptor downregulation and tachyphylaxis. Fine-tuning 5-HT2A Gq-signaling enables development of non-psychedelic 5-HT2A agonists.
PLoS ONE
June 17, 2016
Jason Wallach, Heather Kang, Tristan Colestock et al.
73 citations
1,2-Diarylethylamines such as diphenidine (DPH) and 2-methoxy-diphenidine (2-MXP) are sold as 'legal highs' and have been linked to fatal and non-fatal overdoses. Binding studies at 46 central nervous system receptors show these compounds are relatively selective N-methyl-D-aspartate receptor (NMDAR) antagonists with weak off-target inhibition of dopamine and norepinephrine reuptake. In rats, DPH and 2-MXP significantly reduced prepulse inhibition of startle (PPI), an effect seen with dissociative drugs like phencyclidine (PCP) and ketamine. DPH acted with a median effective dose (ED50) of 9.5 mg/kg, less potent than PCP and ketamine.
Journal of Analytical Toxicology
February 19, 2015
Simon Elliott, Simon D. Brandt, Jason Wallach et al.
54 citations
2-Methoxydiphenidine (2-MXP), a dissociative research chemical sold as an alternative to methoxetamine and ketamine, was detected in post-mortem blood and urine from three fatalities. Femoral blood concentrations were 24.0, 2.0, and 1.36 mg/L; the lowest case had an alternative cause of death. Therapeutic levels of prescription drugs were also present. Metabolites included hydroxy-2-MXP (with hydroxylation on the piperidine ring), O-desmethyl-2-MXP, and hydroxylated O-desmethyl-2-MXP. Diphenidine and hydroxy-diphenidine were detected, but it was unclear if they came from 2-MXP or separate diphenidine use. These are the first published fatalities involving 2-MXP, providing analytical data for forensic toxicologists.
Drug Testing and Analysis
April 15, 2015
Gavin McLaughlin, Noreen Morris, Pierce V. Kavanagh et al.
32 citations
Three powdered samples sold online as the 'research chemical' 2-methoxydiphenidine (2-MXP) were analytically characterized and compared with synthesized isomers. Gas chromatography, high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance spectroscopy, infrared spectroscopy, and thin layer chromatography all confirmed the samples were 2-MXP. The three positional isomers (2-, 3-, and 4-MXP) could be differentiated, notably by distinct stability differences observed during in-source collision-induced dissociation of the protonated molecule under HPLC selected-ion monitoring. Additionally, matrix assisted inlet ionization Orbitrap mass spectrometry detected the protonated molecule of 2-MXP directly from a tablet surface after adding 3-nitrobenzonitrile as matrix.
Drug Testing and Analysis
July 15, 2014
Jason Wallach, Pierce V. Kavanagh, Gavin McLaughlin et al.
26 citations
Diphenidine, a dissociative agent sold as a 'research chemical,' and its isomer 2,2-DEP can be distinguished using gas chromatography-mass spectrometry by their unique iminium ions. The study synthesized and characterized both compounds and their pyrrolidine analogues. Two vendor samples confirmed diphenidine. In rat hippocampal slices, diphenidine (30 μM) reduced NMDA-mediated electrical signals to a similar extent as ketamine (30 μM), indicating it acts on the same receptor. This suggests 1,2-diphenylethylamines are emerging alternatives to arylcyclohexylamine-type dissociatives like PCP and methoxetamine.
Drug testing and analysis
February 1, 2018
Tristan Colestock, Jason Wallach, Matt Mansi et al.
14 citations
A new dissociative anesthetic, 3-MeO-PCMo, a morpholine analogue of 3-MeO-PCP, was synthesized and characterized along with five related compounds. All six arylcyclohexylmorpholines were analyzed using chromatographic, mass spectrometric, and spectroscopic techniques, allowing differentiation of positional isomers. In vitro binding studies in rat forebrain preparations showed moderate affinity for the N-methyl-D-aspartate receptor (NMDAR), with 3-Me-PCMo having the highest affinity, followed by 3-MeO-PCMo. 3-MeO-PCMo had affinity comparable to ketamine and approximately 12-fold lower than PCP. These findings support anecdotal reports of dissociative effects from 3-MeO-PCMo in humans.
bioRxiv (Cold Spring Harbor Laboratory)
July 31, 2023
Jason Wallach, Andrew B. Cao, Maggie M. Calkins et al.
11 citations
preprint
Serotonergic psychedelics show therapeutic promise, but the specific signaling pathways responsible for their effects have been unclear. Researchers developed a series of 5-HT2A receptor ligands with varying Gq efficacies, including β-arrestin-biased ligands. They found that 5-HT2A-Gq efficacy, not β-arrestin2 efficacy, predicts psychedelic potential, measured by head-twitch response in male mice. Disrupting Gq-PLC signaling reduced this response, and a threshold of Gq activation is needed for psychedelic-like effects, explaining why some partial agonists like lisuride are non-psychedelic. β-arrestin-biased agonists caused receptor downregulation and tachyphylaxis, and showed an anti-psychotic-like profile. This fine-tuning of 5-HT2A signaling can generate ligands distinct from classical psychedelics.
Journal of Behavioral and Brain Science
January 1, 2023
Melissa C. Selinger, David M. Compton, Hamilton Morris et al.
3 citations
Managing patients with both chronic pain and major depressive disorder is challenging, and many do not benefit adequately from standard medications. A retrospective review of cases explored patient satisfaction and tolerability of a novel virtual reality protocol used alongside intravenous ketamine infusions. Pain scores on a visual analogue scale were significantly lower on the third treatment day than on the first. Depression ratings also improved after infusions and across sessions. Two-thirds of patients preferred having virtual reality with their ketamine infusion. The findings suggest potential for combination therapy, but prospective studies are needed to confirm any synergistic benefit.