MXP

Methoxphenidine (MXP), also known as 2-MXP or 2-MeO-diphenidine, is a synthetic dissociative in the diarylethylamine family. Although it is often discussed alongside ketamine analogues, it is not an arylcyclohexylamine: its structure contains two phenyl rings and a piperidine group rather than a cyclohexanone ring. MXP appeared on the research-chemical market after the 2013 UK ban on several arylcyclohexylamines.

Chemistry and history

MXP is a methoxy-substituted analogue of diphenidine. Its systematic structure is (±)-1-[1-(2-methoxyphenyl)-2-phenylethyl]piperidine. The methoxy group is attached to the ortho position of one phenyl ring, while the piperidine ring is incorporated into the terminal amine.

MXP and diphenidine became more visible on online research-chemical markets after controls were introduced for several arylcyclohexylamines in the United Kingdom in 2013. MXP was initially marketed as a replacement for methoxetamine, although the two substances belong to different chemical classes and do not have identical effects.

Pharmacology

MXP acts as an NMDA receptor antagonist, producing a dissociative profile. Early descriptions of its pharmacology were based largely on its structure and user reports. More recent animal work has examined its distribution and behavioural effects.

A 2025 study in rats found that MXP crossed the blood-brain barrier rapidly and reached peak concentrations in brain and serum within approximately 30 minutes. The researchers observed increased locomotor activity at lower experimental exposures and reduced activity at higher ones. MXP also disrupted prepulse inhibition, a measure of sensorimotor gating, and showed moderate acute toxicity in the animal model (Štefková-Mazochová and colleagues, 2025).

Subjective effects

The PsychonautWiki profile of MXP includes users’ comparisons with the dissociative effects of ketamine or dextromethorphan. These anecdotal descriptions cannot predict a clinical response.

Physical effects

Reported effects include bodily lightness, a soft vibrating sensation, pain relief and tactile disconnection. Motor coordination and balance may become impaired as the dissociation intensifies. Some users describe the ability to shift their attention between connected and disconnected bodily sensations, although this is a subjective description rather than a measured effect.

Dizziness and gait changes are also reported. The animal study found a shift from stimulation towards sedation as exposure increased, but these results cannot be translated directly into a human experience.

Visual effects

Visual suppression is a recurring feature of user accounts. It may involve reduced acuity, double vision, difficulty recognising patterns and a slowed or fragmented perception of movement. Perspective distortions and changes in the apparent geometry of the environment are also described. More elaborate internal imagery appears less consistently.

Cognitive effects

Users report depersonalisation, derealisation, changes in memory and time perception, conceptual thinking and euphoria. Some describe the experience as relatively clear-headed compared with ketamine or MXE, while others report confusion and impaired analysis. Increased appreciation of music and a dream-like quality to thought are also mentioned.

Auditory effects

Auditory changes include muffled or suppressed sound, altered pitch and delayed or fragmented perception. Some reports describe repeated syllables or echoes, particularly during more intense dissociation.

Clinical toxicity

A 2014 case report described analytically confirmed MXP intoxication in a 53-year-old man who was found somnolent and confused. Clinical findings included tachycardia, severe hypertension, agitation, echolalia, nystagmus, abnormal muscle tone and amnesia. The patient recovered after symptomatic treatment (Hofer and colleagues, 2014).

A later review of adverse events described additional non-fatal cases involving agitation, aggressive behaviour, dissociation and sedation. Hyperthermia, tachycardia and enlarged pupils were among the reported clinical signs (Review of NPS adverse events, 2017–2020).

Research limitations

The 2025 animal study adds information about MXP’s acute behavioural effects and distribution, but does not establish a human toxic range or long-term safety profile. The clinical literature remains small, and there is little information about metabolism, dependence or the effects of repeated exposure.

MXP should also be distinguished from methoxetamine (MXE). Their names are similar, but their structures, chemical classes and available pharmacological findings are different.

Related compounds

MXP is related to Diphenidine and Ephenidine, which are also diarylethylamine dissociatives. It is chemically distinct from Methoxetamine and other arylcyclohexylamines.