Methoxphenidine (methoxydiphenidine, 2-MeO-Diphenidine, MXP) is a dissociative of the diarylethylamine class that has been sold online as a designer drug. Methoxphenidine was first reported in a 1989 patent where it was tested as a treatment for neurotoxic injury. Shortly after the 2013 UK ban on arylcyclohexylamines methoxphenidine and the related compound diphenidine became available on the gray market, where it has been encountered as a powder and in tablet form. Though diphenidine possesses higher affinity for the NMDA receptor, anecdotal reports suggest methoxphenidine has greater oral potency. Of the three isomeric anisyl-substituents methoxphenidine has affinity for the NMDA receptor that is higher than 4-MeO-Diphenidine but lower than 3-MeO-Diphenidine, a structure–activity relationship shared by the arylcyclohexylamines.
Acute methoxphenidine intoxication has been reported to produce confusion, hypertension, and tachycardia that was responsive to treatment with intravenous lorazepam, methoxphenidine has also been associated with three published fatalities and one case of impaired driving
Methoxphenidine (also known as MXP) is a lesser-known novel dissociative substance of the diarylethylamine class that produces dissociative and hallucinogenic effects when administered. It is structurally related to diarylethylamines like diphenidine and ephenidine.
Methoxphenidine is classified as an NMDA receptor antagonist. Members of this class induce a state known as “dissociative anesthesia” and are used in both medical (e.g. surgical anesthesia) and recreational settings. These include arylcyclohexylamines like ketamine and phencyclidine (PCP), as well as dextromethorphan (DXM).
Methoxphenidine along with related diarylethylamines have been studied as treatments for neurotoxic injuries. It has no documented history of non-medical use before the 2013 UK arylcyclohexylamine ban, when it and diphenidine became available in powder and tablet form on the online research chemical market. It was initially marketed as a replacement for methoxetamine (MXE) although users report substantially different effects. It is an example of a designer drug specifically chosen to mimic the functional or structural features of commonly used illicit substances and circumvent government regulation.
Very little data exists about the pharmacological properties, metabolism, and toxicity of methoxphenidine in humans, and it has an extremely limited history of human usage. A number of fatal and non-fatal overdoses have been linked to the abuse of diarylethylamines. Many reports suggest that they may pose different and more pronounced risks than traditional dissociatives. It is highly advised to use harm reduction practices if using this substance.