Methoxphenidine

1-[1-(2-methoxyphenyl)-2-phenylethyl]piperidine

Overview

Methoxphenidine belongs to Dissociatives.

Key safety note: Methoxphenidine is a potent, long-acting dissociative sold only as an unregulated research chemical, so purity and dose are uncertain and overshooting is easy: especially given its slow onset (30–60 min), which tempts dangerous redosing before the first dose is felt.[4][3]
Effects
Subjective effects vary. What a substance feels like depends on dose, individual physiology, mindset, and setting. The points below describe commonly reported effects, not guaranteed, uniform, or desirable outcomes.
  • Dissociation with depersonalisation and derealisation, detachment from the body, euphoria, conceptual/'philosophical' thinking and increased music appreciation: often described as clearer-headed than other dissociatives.
  • Tactile and motor disconnection, numbness, ataxia and loss of coordination. At higher doses visual distortions, hallucinations and an anaesthetic 'hole'.
  • Sympathetic stimulation (raised heart rate and blood pressure). The comedown and after-effects can include confusion, lingering dissociation and low mood.
Dosing & duration
Harm-reduction note: These are commonly cited reference ranges, not a recommendation or a “safe” dose. Potency, purity, body chemistry, tolerance, and drug combinations vary widely. Start low, go slow, wait for full effects before redosing, and never assume an unknown product matches these figures. Missing data is not evidence of safety.

Oral or insufflated. Values below are approximate ORAL figures. MXP is long-acting with a slow onset.. MXP has a slow onset (30–60 min) and a long duration (6–8 h), so redosing before the first dose is felt is a common cause of overdose: wait well beyond the expected onset. It is sold as a research chemical of uncertain purity, so start low with an accurate milligram scale, and avoid combining with other depressants or stimulants.

Dose ranges

Threshold

30 mg

Light

50–75 mg

Common

75–120 mg

Strong

120–150 mg

Heavy

150 mg +

Duration

onset

30–60 min

total

6–8 h

after effects

1–3 h

Chemical & Physical Properties
FormulaC20H25NO
Molar mass295.4 g/mol
StateSolid (usually the hydrochloride salt, crystalline)
Melting pointNot reported
Boiling pointNot reported
DensityNot reported
Vapor pressureNot reported
pKaNot reported
LogP4.6 (predicted, XLogP3)
SolubilityNot reported
Refractive indexNot reported
Identifiers & Synonyms
CASNot reported
CAS (enantiomer)
PubChem CID67833251
InChIKeyQXXCUXIRBHSITD-UHFFFAOYSA-N
InChIInChI=1S/C20H25NO/c1-22-20-13-7-6-12-18(20)19(21-14-8-3-9-15-21)16-17-10-4-2-5-11-17/h2,4-7,10-13,19H,3,8-9,14-16H2,1H3
SMILESCOC1=CC=CC=C1C(CC2=CC=CC=C2)N3CCCCC3

Synonyms

  • MXP
  • 2-MeO-Diphenidine
  • 2-MeO-DPH
  • Methoxydiphenidine
Pharmacodynamics & Biochemistry

Methoxphenidine (MXP, 2-MeO-diphenidine) is a dissociative of the diarylethylamine class, the 2-methoxy analogue of diphenidine, and, like ketamine and PCP, an antagonist of the NMDA glutamate receptor. It is an open-channel blocker: once glutamate opens the receptor, MXP binds within the pore at the PCP/dizocilpine (MK-801) site and blocks cation flux in a use- and voltage-dependent way. Wallach et al. (2016) measured an NMDA affinity of Ki ≈ 36 nM ([3H]MK-801, rat forebrain): high, though somewhat weaker than diphenidine (~18 nM). Anecdotally MXP is nonetheless the more orally potent of the two, probably reflecting better oral bioavailability. Beyond the NMDA channel it is fairly selective: it binds the dopamine transporter only weakly (Ki ≈ 2.9 µM), shows moderate affinity at the σ1/σ2 receptors, and has no meaningful serotonin-transporter activity. This NMDA-dominant profile produces the dissociative state: detachment from body and surroundings, analgesia, disordered sensory integration and, at high doses, anaesthesia, and MXP is noted for an unusually long duration and a comparatively 'clear-headed' character. It is used as the racemate.

Biological targets

  • NMDA

Binding & functional measurements

TargetMeasurementSpecies
NMDA receptorKi 36 ± 3.7 nMRat
Dopamine transporterKi 2,915 nMHuman
Pharmacokinetics
BioavailabilityNot reported
TmaxNot reported
Half-lifeNot established in humans. Reported subjective effects of 6–8 h are not an elimination half-life.
VdNot reported
Protein bindingNot reported
MetabolismHepatic: O-demethylation, aromatic/aliphatic hydroxylation and N-dealkylation, then conjugation
ExcretionRenal
Toxicology & Safety
Harm-reduction note: Toxicity and risk depend on dose, route, purity, combinations, setting, and individual health factors. Missing harms should never be interpreted as evidence of safety.

Not reported

Methoxphenidine is a potent, long-acting dissociative sold only as an unregulated research chemical, so purity and dose are uncertain and overshooting is easy: especially given its slow onset (30–60 min), which tempts dangerous redosing before the first dose is felt. Effects include heavy dissociation, ataxia and loss of coordination, confusion, nausea, and, via its sympathomimetic action, raised heart rate and blood pressure (hypertension and tachycardia are typical features of MXP intoxication). High doses can produce an anaesthetic 'hole' with immobility and vomiting (aspiration risk), agitation and acute psychosis. A number of psychotic episodes and at least three fatalities have been reported, and MXP was implicated in a widely reported homicide. Its long duration and delayed onset strongly encourage compulsive redosing, and combining it with other depressants (alcohol, benzodiazepines, opioids) or stimulants sharply raises the danger.[4][3]

Legal Status
Legal note: Legal status can change over time and may vary by country, region, formulation, analogue status, prescription context, and enforcement practice. Always confirm with current official sources before relying on this section.
Interactions & Contraindications

Drug interactions

Alcohol, Benzodiazepines, Opioids Additive sedation and airway or respiratory risk, worsened by vomiting.[4][3]
Stimulants (amphetamines, cocaine) Mask the dissociation and add cardiovascular strain, as MXP itself raises heart rate and blood pressure.[4]

Contraindications

Cardiovascular disease, hypertension or arrhythmia[4]
Personal or family history of psychosis, schizophrenia or bipolar disorder history of psychosis or severe anxiety.[4]
Combining with alcohol or other CNS depressants or concurrent stimulants.[4]
Settings where impairment or dissociation risks injury (driving, water, heights) anything needing coordination or alertness, e.g. driving.[5]
Usage & Context
  • A recreational dissociative sold from around 2013 as an unregulated 'research chemical' and ketamine/diphenidine substitute, usually swallowed or insufflated, valued for a long, comparatively clear-headed dissociative state.
  • It emerged as one of the diarylethylamine dissociatives that filled the gap left when arylcyclohexylamine (ketamine-type) dissociatives were banned. It has no medical use.
  • It has been linked to hospital presentations, impaired driving and fatalities, and is now restricted in many countries.
Sources & Evidence

Further Information