Methoxetamine

# Research Output: Methoxetamine (MXE)

**PSX ID:** PSX-0253  
**Research date:** 2026-05-03  
**Provenance ID:** fe6a3a77-1a00-48cc-b812-aaac20757165

---

## Chemical Identity

**Verified against PubChem CID 52911279** [Ref 36]:

| Property | Value | Source |
|---|---|---|
| PubChem CID | 52911279 | PubChem [Ref 36] |
| Molecular formula | C₁₅H₂₁NO₂ | PubChem [Ref 36] |
| Molecular weight | 247.33 g/mol | PubChem [Ref 36] |
| IUPAC name | 2-(ethylamino)-2-(3-methoxyphenyl)cyclohexan-1-one | PubChem [Ref 36] |
| InChIKey | LPKTWLVEGBNOOX-UHFFFAOYSA-N | PubChem [Ref 36] |
| CAS (free base) | 1239943-76-0 | Web-retrieved [Ref 31] |
| CAS (HCl salt) | 1239908-48-5 | Web-retrieved [Ref 31] |
| Melting point (HCl) | 227–233°C | Web-retrieved |
| Solubility (HCl) | Ethanol: 10 mg/mL; DMSO: 14 mg/mL; PBS: 5 mg/mL | Web-retrieved |

**Structural notes:** MXE is structurally derived from ketamine by replacing the 2-chloro substituent on the aryl ring with a 3-methoxy group, and adding an N-ethyl rather than N-methyl amino group. As De Paoli et al. (2013 [Ref 26]) confirmed from street samples via GC-MS and NMR, the compound is 2-(ethylamino)-2-(3-methoxyphenyl)cyclohexanone. The racemic (RS) mixture is sold recreationally.

**Seed data discrepancies:** The brief listed no SMILES, molecular formula, molecular weight, InChIKey, or PubChem CID. All have been confirmed above via PubChem CID 52911279.

---

## Pharmacology

### Primary Receptor Targets

#### NMDA Receptor (PCP-channel binding site)
MXE acts as a non-competitive, open-channel blocker of the NMDA receptor at the phencyclidine (PCP) binding site. Roth et al. (2013 [Ref 1]) determined the binding affinity via NIMH Psychoactive Drug Screening Program (PDSP) radioligand assays: **Ki = 337 ± 76 nM** (n=3), compared with the reference compound MK-801 (Ki = 5.7 ± 0.57 nM). MXE thus has high affinity for the PCP site, comparable to or exceeding ketamine itself. Halberstadt et al. (2016 [Ref 2]) confirmed that this PCP-site affinity is the primary pharmacological feature underlying MXE's dissociative behavioral profile, which includes locomotor hyperactivity and disruption of prepulse inhibition (PPI) of acoustic startle in rodents.

#### Serotonin Transporter (SERT)
Roth et al. (2013 [Ref 1]) reported **Ki = 479 nM** at SERT from radioligand binding assays. This places MXE as a clinically meaningful serotonin reuptake inhibitor, distinct from ketamine itself, which has minimal SERT activity. This serotonergic component has pharmacological implications for both therapeutic potential and drug interaction risk.

#### 5-HT₂ Receptors
Marti et al. (2021 [Ref 41]) provided the first in vivo mechanistic evidence that 5-HT₂ receptors are critical mediators of MXE's behavioral effects. Using selective 5-HT₂ antagonists (ketanserin and MDL 100907 at non-behaviorally active doses), they demonstrated that blockade of 5-HT₂ receptors:
- Attenuated MXE-induced facilitation of motor responses
- Prevented MXE-induced inhibition of visual sensory responses
- Blocked MXE-induced PPI reduction
In vivo microdialysis confirmed that MXE (0.25–0.5 mg/kg i.v.) significantly elevated serotonin levels in rat medial prefrontal cortex and nucleus accumbens. Botanas et al. (2017 [Ref 7]) further showed that ketanserin (a 5-HT₂ antagonist) blocked MXE's antidepressant effect in the forced swim test, and Botanas et al. (2021 [Ref 6]) confirmed that both R-MXE and S-MXE increased 5-HT2a and 5-HT2c receptor mRNA in the prefrontal cortex.

#### GABA System
Marti et al. (2021 [Ref 41]) demonstrated in electrophysiological studies that MXE inhibits GABA-mediated spontaneous inhibitory postsynaptic currents in a concentration-dependent manner. MXE did not alter the AMPA component of field potentials or presynaptic glutamate release, and did not interfere with endocannabinoid-mediated GABAergic synapses.

#### mTOR/AMPA Pathway (Antidepressant Mechanism)
Botanas et al. (2017 [Ref 7]) demonstrated that NBQX (an AMPA receptor antagonist) blocked MXE's antidepressant effects in mice, implicating downstream AMPA receptor activation. Botanas et al. (2021 [Ref 6]) confirmed that both MXE enantiomers increased mTOR phosphorylation and elevated AMPA receptor subunits GluA1 and GluA2 protein levels in hippocampus and prefrontal cortex, and increased gamma wave activity (EEG). This mechanistic cascade—NMDA blockade → AMPA upregulation → mTOR phosphorylation → synaptic plasticity—parallels ketamine's antidepressant mechanism.

#### Sigma-1 Receptor / Dopamine / Opioid Receptors
Coppola & Mondola (2012 [Ref 8]) proposed that MXE acts as an agonist at dopamine D2, serotonin 5-HT₂, muscarinic cholinergic, sigma-1, opioid mu, and kappa receptors in a hypothesis paper. **FLAG:** These receptor actions at sigma-1, dopamine D2, opioid mu/kappa, and muscarinic receptors are not confirmed by published primary binding data. Roth et al.'s (2013 [Ref 1]) comprehensive NIMH PDSP screening of 57 molecular targets found no notable affinity at these sites. The Coppola & Mondola claims are hypothesis-level and should not be presented as established pharmacology.

### Mesolimbic Dopamine Enhancement
Mutti et al. (2016 [Ref 5]) demonstrated that MXE enhances mesolimbic dopaminergic transmission and substitutes for ketamine in self-administration paradigms. This indirect effect is mechanistically consistent with NMDA-mediated disinhibition of GABAergic interneurons in the ventral tegmental area, releasing tonic inhibition of dopamine projection neurons—the same mechanism proposed for ketamine.

### Stereochemistry
MXE is sold as a racemic (RS) mixture. Botanas et al. (2021 [Ref 6]) is the definitive comparative study:
- **R(−)-MXE**: Antidepressant effects comparable to S-MXE; **does not** produce CPP, hyperlocomotion, PPI deficits, or locomotor sensitization; acutely alters motor coordination. **Fewer behavioral side effects and lower abuse liability.**
- **S(+)-MXE**: Antidepressant effects; **does** produce CPP, hyperlocomotion, PPI deficits, locomotor sensitization. Higher abuse liability profile.
- Both enantiomers show NMDA receptor affinity and SERT inhibition.
- Both enantiomers increase gamma waves, mTOR phosphorylation, GluA1/GluA2 levels, 5-HT2a/c mRNA.

### Pharmacokinetics (Animal Data — No Human PK Study Published)

Horsley et al. (2016 [Ref 22]; Prague group, Wistar rats, 10 mg/kg s.c.) provide the most detailed PK profile:
- **Brain accumulation**: Brain:serum ratio = 2.06–2.93 throughout observation period
- **Tmax (brain)**: 30 minutes post-administration
- **Duration in brain**: High at 60 min; progressive decline, near-zero by ~6 hours
- **Primary metabolites in urine**: O-desmethylmethoxetamine (most abundant) > normethoxetamine
- **Duration of behavioral effects**: 60–90 minutes at low doses (5 mg/kg); sedation/anaesthesia at 40 mg/kg

Meyer et al. (2013 [Ref 14]) identified CYP enzyme involvement via in vitro human microsomal studies:
- **Initial metabolic step (N-deethylation)**: Catalyzed by **CYP2B6 and CYP3A4**
- Subsequent steps: O-demethylation, hydroxylation, and combinations
- Phase II: glucuronidation and sulfation
- Eight metabolites identified in rat and human urine

Menzies et al. (2014 [Ref 15]) confirmed phase I and II metabolites in urine from three patients with acute MXE toxicity:
- Phase I: normethoxetamine, O-desmethylmethoxetamine, dihydromethoxetamine, dehydromethoxetamine, hydroxymethoxetamine isomers, hydroxynormethoxetamine
- Phase II: glucuronide conjugates of O-desmethylmethoxetamine, O-desmethylnormethoxetamine, O-desmethylhydroxymethoxetamine

**FLAG:** No human pharmacokinetic study (bioavailability, human Tmax, human half-life) has been published. All PK data are from animal models or extrapolated from case-report drug concentrations.

---

## History

### Discovery and Synthesis
MXE was designed as a structural modification of ketamine, replacing the 2-chloro group with a 3-methoxy substituent and extending the N-methyl to N-ethyl to create a longer-acting analogue. The compound was reportedly intended by an "underground chemist" to be a "stress-free version of ketamine"—simultaneously more potent, longer-acting, and purportedly free from ketamine's urological side effects (Corazza et al. 2012 [Ref 13]).

Web-retrieved sources attribute MXE's initial synthesis to approximately 2006, with effects first described online in May 2010. The compound became commercially available on a small scale in September 2010 (Corazza et al. 2012 [Ref 13]). By November 2010, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) had formally identified MXE through its Early Warning System. By July 2011, the EMCDDA identified 58 websites selling MXE at approximately 145–195 euros per 10 g. **FLAG:** The attribution to William Mathew Eibeck as original synthesizer comes from web sources only and could not be verified against published literature.

### Market History
Horsley et al. (2016 [Ref 22]) document that MXE "emerged in 2010 as a substitute for the dissociative anaesthetic ketamine." It was actively marketed as a "bladder-friendly" and safer ketamine alternative (Dargan et al. 2014 [Ref 39]; Corazza et al. 2013 [Ref 12]). Corazza et al. (2013 [Ref 12]) coined the name "Special M" (analogous to ketamine's street name "Special K") in their review of MXE's recreational use arc.

Corazza et al. (2012 [Ref 13]) documented MXE's availability through online "legal high" shops during 2010–2012, characterizing its rapid dissemination as a public health challenge requiring international regulatory response.

### Regulatory/Legal History (Timeline)
- **November 2010**: EMCDDA Early Warning System formally identifies MXE (Hajkova et al. 2016 [Ref 29])
- **January 2011**: Canada declares MXE a Schedule I analogue under CDSA [Ref 32]
- **April 2012**: UK Home Office places MXE under temporary class drug control (prohibiting import/sale for 12 months) [Ref 30]
- **February 26, 2013**: UK — MXE permanently classified as Class B drug under Misuse of Drugs Act [Ref 30]
- **August 2013**: France — MXE classified as narcotic (noted in Imbert et al. 2014 [Ref 17])
- **2014**: European Union — European Commission proposes MXE ban across EU following EMCDDA risk assessment [Ref 31]
- **March 2016**: UN Commission on Narcotic Drugs (CND, 59th Session) — MXE placed in Schedule II of the 1971 Convention on Psychotropic Substances (CND Dec/59/6) [Ref 32]
- **December 7, 2021**: US DEA — Notice of Proposed Rulemaking to permanently place MXE in Schedule I [Ref 31]
- **July 6, 2022**: US — MXE finalized as Schedule I controlled substance (DEA) [Ref 31]
- **Australia**: Controlled via analogues provisions of the scheduling framework

---

## Subjective Effects

### Published Human Data
The only published human survey data on MXE subjective effects is Winstock et al. (2016 [Ref 10]), conducted in a UK clubbing/polydrug-using sample. This survey documented:
- Motivations for use: curiosity, recreation, perceived safer alternative to ketamine
- Effect profile: dissociative, analgesic, dissociation from body/reality
- Users noted longer duration than ketamine and greater intensity at equivalent doses

### Effects from Online/Forum Analysis
Corazza et al. (2012 [Ref 13]) systematically analyzed online reports, drug forums, and community discussion boards. Key documented effects included:
- Dissociation and depersonalization
- Hallucinations (visual and internal)
- Analgesia
- Near-death/K-hole type experiences
- Perceptual distortion
- Longer duration than ketamine (effects persisting 4–6 hours reported)

### Published Animal and Clinical Behavioral Data
Halberstadt et al. (2016 [Ref 2]) and Horsley et al. (2016 [Ref 22]) established the behavioral pharmacology in rodents:
- **Low doses** (5–10 mg/kg s.c. rats): Locomotor stimulation, anxiogenesis (thigmotaxis, decreased time in center)
- **High doses** (40 mg/kg s.c. rats): Sedation/anaesthesia, stereotypy
- PPI disruption at all doses (consistent with psychotomimetic action)
- Duration: effects present 60–90 min at lower doses; longer at higher doses
- Dissociative anesthetic behavioral profile confirmed (Ossato et al. 2018 [Ref 3])

Berquist et al. (2018 [Ref 4]) noted that MXE produced PCP-like interoceptive effects in drug discrimination but with **reduced locomotor stimulant effects** compared to PCP—suggesting a somewhat different profile despite NMDA-mediated overlap.

Costa et al. (2019 [Ref 16]) found that repeated low-dose MXE (0.1–0.5 mg/kg every other day × 5 doses) produced **persistent behavioral abnormalities** 8 days post-challenge: increased anxiety (elevated plus maze), impaired non-spatial memory (novel object recognition), and marble burying alterations in rats.

### Dose–Duration Relationship
Horsley et al. (2016 [Ref 22]) found that MXE's duration of behavioral action exceeds ketamine's, consistent with its accumulation in brain tissue (B:S ratio 2.06–2.93) and slower release. Brain levels peak at 30 min and remain elevated at 60 min, declining to near-zero by ~6 hours. This pharmacokinetic profile is compatible with the community-reported 4–6 hour oral duration in the brief's seed data. **FLAG:** Dose data (thresholds, common/strong/heavy) in the brief are community-derived and have not been validated in controlled human dosing studies.

---

## Safety & Toxicity

### Acute Toxicity — No LD50 Established
No LD50 has been established for MXE in humans. The evidence hierarchy is:

**Single-substance confirmed fatality:**
Adamowicz & Zuba (2015 [Ref 23]) reported the first published single-substance MXE fatality. Blood MXE concentration at post-mortem: **5.8 µg/mL** (5800 µg/L). This is the source of the seed data figure. Full toxicological details beyond blood concentration are limited in the abstract.

**Polydrug fatalities:**
1. Wikström et al. (2013 [Ref 35]): 26-year-old male found dead. Femoral blood MXE: **8.6 µg/g**. Synthetic cannabinoids also present (AM-694, AM-2201, JWH-018, THC). Circumstances point to unintentional acute MXE intoxication, though cannabinoids may have contributed. Reference blood concentrations from living MXE users (4 cases): **0.13–0.49 µg/g**.

2. Wiergowski et al. (2014 [Ref 24]): 31-year-old male admitted in deep coma (GCS unspecified). Serum MXE **0.32 µg/mL** (toxic range); serum amphetamine 0.06 µg/mL (non-toxic range). Clinical course: **hyperthermia >39°C, generalized seizures, marked leukocytosis, massive rhabdomyolysis, hepatic failure, acute renal failure, multi-organ dysfunction syndrome**. Died 4 weeks post-poisoning. This is the published basis for the seed data's polydrug toxicity characterization.

3. Bursová et al. (2024 [Ref 18]): 42-year-old known drug user found dead approximately 2 months after death. Blood MXE: **3.6 ng/mL**; urine: 70.5 ng/mL; gastric: 18.0 ng/mL. No other drugs, medications, or poisons found. Authors concluded MXE contributed to death.

4. Chiappini et al. (2015 [Ref 25]) provided an overview of UK MXE-related deaths in 2011–2013 from national data.

5. Elliott & Evans (2014 [Ref 34]) documented MXE in UK forensic casework (2010–2012) as one of the most frequently detected NPS.

### Acute Clinical Toxicity — Non-Fatal Cases

**Cerebellar toxicity (reversible):**
Shields et al. (2012 [Ref 11]) reported three analytically confirmed cases presenting with acute neurological toxicity. All featured **reversible cerebellar toxicity** — a distinctive and potentially diagnostic presentation for high-dose MXE exposure.

**Cardiovascular toxicity:**
Imbert et al. (2014 [Ref 17]) documented a 21-year-old male after intranasal MXE inhalation:
- **Sinus bradycardia**: 48 bpm
- **ST-segment elevation** on ECG
- **Elevated creatine kinase**: 270 U/L
- **Hyponatremia**: 127 mmol/L
- New seizure activity during hospitalization
- Serum MXE: 30 µg/L; urine: 408 µg/L
- Favorable outcome after ICU care
This case provides the published basis for the seed data's cardiovascular toxicity characterization (bradycardia, ST-elevation).

**Other documented presentations:**
- Extreme agitation, aggression, confusion, hallucinations, amnesia, tachycardia (Łukasik-Głębocka et al. 2013 [Ref 27]; serum 270 ng/mL, urine 660 ng/mL)
- Seizures, dissociation, respiratory compromise (Noguè et al. 2015 [Ref 19]; Misselbrook & Hamilton 2012 [Ref 20])

### Neurotoxicity (Animal Data)
Costa et al. (2019 [Ref 16]) is the first in vivo demonstration of MXE neurotoxicity. Repeated MXE (0.1–0.5 mg/kg every other day × 5, i.p., rats) produced:
- **Dopaminergic damage**: Reduced dopamine transporter and tyrosine hydroxylase density in medial prefrontal cortex, nucleus accumbens, caudate-putamen, substantia nigra pars compacta, and ventral tegmental area
- **Serotonergic damage**: Reduced serotonin transporter density in nucleus accumbens
These changes were still present 8+ days post-challenge. **Species note: all neurotoxicity data are from rats. No published human neuroimaging or neuropathological data for MXE exposure exist.**

### Bladder and Renal Toxicity — CRITICAL SEED DATA FLAG

**The brief's seed data states: "Bladder toxicity uncharacterized despite 'bladder safe' marketing claim." This is INCORRECT.** Two published animal studies have characterized MXE bladder/renal toxicity:

1. **Dargan et al. (2014 [Ref 39])** — Mice, 3 months daily 30 mg/kg i.p.:
   - Significant **bladder toxicity**: inflammatory changes with subsequent fibrosis
   - Significant **renal toxicity**: changes at tubular and glomerular level
   - MXE marketed as "bladder friendly" but the authors explicitly state "there is no data to be able to substantiate this claim"

2. **Wang et al. (2017 [Ref 40])** — Female rats, 30 mg/kg/day i.p. for 4 or 12 weeks:
   - Increased micturition frequency, bladder dysfunction (cystometry)
   - Damaged urothelium barriers
   - Inflammatory cell infiltration, matrix deposition
   - Elevated pro-inflammatory cytokines: IL-1β, IL-6, CCL-2, CXCL-1, CXCL-10, NGF, COX-2
   - Interstitial fibrosis: collagen I, collagen III, fibronectin, TGF-β
   - Direct toxic and pro-inflammatory effects on **human urothelial cells** confirmed in vitro
   - Changes comparable to ketamine-induced cystitis

**FLAG FOR GENERATION AGENT:** The bladder toxicity section must NOT state that bladder toxicity is uncharacterized. It has been characterized in mice and rats and in human urothelial cells in vitro. What remains absent is published human case reports of MXE-associated bladder pathology — but absence of published reports is not absence of risk.

### Organ Toxicity Summary
| Organ/System | Evidence Tier | Key Source |
|---|---|---|
| CNS (cerebellar) | Human case series | Shields et al. 2012 [Ref 11] |
| Cardiovascular | Human case report | Imbert et al. 2014 [Ref 17] |
| Skeletal muscle (rhabdomyolysis) | Human case report (polydrug) | Wiergowski et al. 2014 [Ref 24] |
| Hepatic | Human case report (polydrug) | Wiergowski et al. 2014 [Ref 24] |
| Renal | Animal (mice) + human case | Dargan et al. 2014 [Ref 39]; Wiergowski 2014 [Ref 24] |
| Bladder | Animal (mice + rats) + human cells in vitro | Dargan 2014 [Ref 39]; Wang 2017 [Ref 40] |
| Dopaminergic/serotonergic | Animal (rats) | Costa et al. 2019 [Ref 16] |

---

## Harm Reduction

### Risk Factors from Literature
1. **Polydrug combinations**: The majority of MXE fatalities and serious adverse events involve combinations with other CNS depressants or stimulants. MXE + CNS depressants (alcohol, GHB, opioids, synthetic cannabinoids) compound sedation and respiratory depression risk. MXE + stimulants (amphetamine) may precipitate hyperthermia, rhabdomyolysis, cardiovascular crisis (Wiergowski et al. 2014 [Ref 24]).

2. **SERT inhibition + other serotonergic drugs**: MXE's Ki of 479 nM at SERT [Ref 1] raises theoretical serotonin syndrome risk when combined with other serotonergic agents (MAOIs, SSRIs, tramadol, MDMA). **FLAG:** No published human case of MXE-associated serotonin syndrome was identified. The risk is inferred from pharmacological mechanism, not confirmed in case reports.

3. **Tramadol**: Listed as "lethal" in the brief. Tramadol inhibits serotonin and norepinephrine reuptake and has weak mu-opioid activity; combining with MXE (SERT inhibitor + CNS depressant) creates dual serotonergic risk plus CNS/respiratory depression. **FLAG:** No specific MXE + tramadol fatality case was found in the published literature. The "lethal" designation appears extrapolated from pharmacological class reasoning rather than documented cases.

4. **GHB/GBL**: Listed as "lethal" in the brief. GHB/GBL are potent CNS depressants; additive depression with MXE's sedative/dissociative effects is mechanistically plausible and consistent with known GHB polydrug fatality patterns. **FLAG:** No MXE + GHB-specific published case was identified.

5. **AMT**: Listed as "lethal" in the brief. AMT (alpha-methyltryptamine) is a monoamine releasing agent and MAO inhibitor, creating serotonin syndrome risk when combined with SERT inhibitors. **FLAG:** No MXE + AMT-specific published case was identified.

6. **Dosing precision**: The longer duration and delayed onset (especially oral ROA) increases redosing risk. Community reports note the extended onset as a major factor in accidental overdose (redosing before first dose peaks).

### Analytical Detection
- **Immunoassay**: May yield false positives for amphetamines (case documented: Fassette & Martinez 2016 [Ref 27]) — important for clinical and forensic settings
- **Confirmatory methods**: GC-MS and LC-MS/MS validated for blood, urine (De Paoli et al. 2013 [Ref 26]; Meyer et al. 2013 [Ref 14])
- **Hair testing**: MXE and metabolites detectable in hair up to 2.5 months prior (Imbert et al. 2014 [Ref 17]; Matey et al. 2022 [Ref 21])
- **Post-mortem stability**: MXE and metabolites detectable in decomposed body 2 months post-mortem (Bursová et al. 2024 [Ref 18])

### Emergency Management (from published cases)
Across documented cases (Shields 2012 [Ref 11], Imbert 2014 [Ref 17], Noguè 2015 [Ref 19], Misselbrook 2012 [Ref 20]):
- Supportive care in monitored setting
- Benzodiazepines for agitation and seizure control (noted as having "slight response" in some cases — Łukasik-Głębocka 2013 [Ref 27])
- Cardiac monitoring for arrhythmia / ST changes
- Monitoring for rhabdomyolysis (CK, renal function)
- No specific antidote published

---

## Tolerance & Dependence

### Tolerance
**FLAG:** The brief states a tolerance half-life of ~5 days and full reset of ~10 days as "community_consensus_small." No published pharmacological or clinical study has characterized MXE tolerance development rates in humans or animals. Cross-tolerance with other NMDA receptor antagonists (ketamine, PCP, dextromethorphan) is mechanistically plausible but unconfirmed by MXE-specific published data. The tolerance values in the brief should be labeled as community estimates without scientific verification.

Berquist et al. (2018 [Ref 4]) demonstrated MXE substitutes for PCP in drug discrimination and reverses PCP withdrawal signs in rats, confirming cross-tolerance at the receptor level.

### Dependence and Abuse Potential
Published animal evidence confirms abuse potential:

1. **Conditioned Place Preference**: Botanas et al. (2015 [Ref 9]) — MXE (2.5 and 5 mg/kg) induced CPP comparable to ketamine (5 mg/kg) in Sprague-Dawley rats. MXE did not alter locomotor activity, unlike ketamine.

2. **Self-Administration**: Botanas et al. (2015 [Ref 9]) — Rats showed modest self-administration (0.25, 0.5, 1.0 mg/kg/infusion). Berquist et al. (2018 [Ref 4]) confirmed MXE is a less effective reinforcer than PCP.

3. **Mesolimbic Dopamine**: Mutti et al. (2016 [Ref 5]) — MXE substituted for ketamine in self-administration and enhanced mesolimbic dopaminergic transmission.

**FLAG:** No human dependence case series, clinical dependence assessment, or withdrawal characterization has been published for MXE. Physical and psychological dependence are classified as "moderate" in the brief — this is consistent with, but extrapolated from, the animal self-administration data above. The "moderate" rating cannot be verified against any published human clinical study.

---

## Interactions

### Published / Mechanistically Characterized

| Interaction | Brief Severity | Evidence Type | Notes |
|---|---|---|---|
| Alcohol | lethal | Mechanistic (CNS depression) | No MXE + alcohol fatality case found in literature; risk extrapolated from class |
| GHB/GBL | lethal | Mechanistic (CNS depression) | No MXE + GHB fatality case found in literature |
| AMT | lethal | Mechanistic (serotonin) | AMT is MAOI + releaser; SERT inhibition from MXE + MAO inhibition = serotonin syndrome risk |
| Tramadol | lethal | Mechanistic (serotonin + opioid) | Tramadol is SNRI + opioid; SERT overlap with MXE raises serotonin syndrome risk |
| Amphetamine | polydrug fatality documented | Case report | Wiergowski et al. 2014 [Ref 24]: MXE 0.32 µg/mL + amphetamine → rhabdomyolysis, multi-organ failure, death |
| Synthetic cannabinoids | polydrug fatality documented | Case report | Wikström et al. 2013 [Ref 35]: MXE 8.6 µg/g + AM-694/AM-2201/JWH-018/THC → death |
| Venlafaxine | possibly fatal | Case report (different drug) | Theofel et al. 2019 [Ref 30] documented N-ethyldeschloroketamine fatality with venlafaxine — suggests risk class pattern for SERT-active dissociatives + SNRIs |

**FLAG:** The "unknown" interaction ratings for many stimulants (2-FMA, 4-FA, cocaine, fenethylline, methamphetamine, lisdexamfetamine, MDMA, etc.) in the brief are accurate — no published MXE-specific interaction data exist for these pairs. The interaction risks for GHB and tramadol (rated "lethal") are pharmacologically plausible but lack documented published cases specific to MXE.

The SERT inhibition confirmed by Roth et al. (2013 [Ref 1]) at Ki = 479 nM means any combination with serotonergic drugs carries serotonin syndrome risk. This particularly concerns: tramadol, MAOIs, SSRIs, SNRIs, MDMA, and AMT.

---

## Legal Status

| Jurisdiction | Status | Date | Source |
|---|---|---|---|
| United Kingdom | Class B (Misuse of Drugs Act) | February 26, 2013 (temporary class April 2012) | UK Gov [Ref 30] |
| Canada | Schedule I (CDSA analogue) | January 2011 | Web-retrieved [Ref 32] |
| France | Narcotic | August 2013 | Imbert et al. 2014 [Ref 17] |
| European Union | Controlled | 2014 | EMCDDA risk assessment |
| UN (International) | Schedule II (1971 Convention) | March 2016 (CND 59th Session) | Federal Register [Ref 32] |
| United States | Schedule I (DEA) | July 6, 2022 (NPRM December 7, 2021) | Federal Register [Ref 31] |
| Australia | Controlled (analogue provisions) | Ongoing | Web-retrieved |

**FLAG:** Australia's exact scheduling date was not confirmed in published literature. Canada's Schedule I status (analogue) was web-retrieved and should be verified against Health Canada primary sources.

---

## Clinical Trials

No clinical trials for methoxetamine were identified on ClinicalTrials.gov (search conducted 2026-05-03). The single returned result (NCT06747520) was for methoxyethyl etomidate hydrochloride — an entirely different compound. MXE has no registered human trials.

Despite multiple animal studies showing antidepressant potential (Botanas et al. 2017, 2021 [Refs 7, 6]), MXE's controlled/scheduled status in major jurisdictions makes human clinical trials unlikely in the near term. The R(−)-MXE enantiomer [Ref 6] has been identified as a candidate for development given its reduced abuse liability profile.

---

## Community Feedback Analysis

No community feedback was submitted in Part A2 of the brief.

---

## Gaps & Flags

### 🚩 CRITICAL — Seed Data Error (Must Correct)
1. **Bladder toxicity**: The seed data states "Bladder toxicity uncharacterized despite 'bladder safe' marketing claim." This is factually incorrect. Dargan et al. (2014 [Ref 39]) and Wang et al. (2017 [Ref 40]) have published animal studies demonstrating significant bladder inflammation, fibrosis, and renal changes following chronic MXE administration. Direct toxicity to human urothelial cells was also confirmed in vitro. The only gap is published human case reports of MXE-associated bladder disease — but the claim of "uncharacterized" needs correction.

### ⚠️ SAFETY-CRITICAL FLAGS (Editorial Review Required)
2. **Interaction severities unverified**: Interactions rated "lethal" for GHB, GBL, tramadol, AMT, and alcohol in the brief are mechanistically plausible but lack published MXE-specific case documentation. Only the amphetamine (Wiergowski 2014 [Ref 24]) and synthetic cannabinoid (Wikström 2013 [Ref 35]) combinations have published case support.

3. **Dose/duration data**: All dose thresholds (threshold, light, common, strong, heavy) are community-derived; no controlled human dosing study has been conducted. These values should be clearly labeled as community consensus, not clinical data.

4. **Tolerance values**: The 5-day half-life and 10-day full reset are community consensus with no published scientific basis.

5. **Sigma-1, opioid, D2, muscarinic receptor activity**: Proposed in Coppola & Mondola 2012 [Ref 8] as a hypothesis but not confirmed by primary binding data from the NIMH PDSP screen (Roth 2013 [Ref 1]).

### ℹ️ DATA GAPS (Not Errors — True Gaps)
6. **No human pharmacokinetic study**: Bioavailability, human Tmax, human elimination half-life, protein binding — all unknown from published literature.

7. **No LD50 established**: No animal or human LD50 data for MXE. The blood concentrations from fatalities (0.32–8.6 µg/g) provide some reference range.

8. **No human bladder pathology case reports**: While animal studies confirm bladder toxicity risk, no published human case of MXE-associated uropathy/cystitis has been identified (distinct from the well-documented ketamine-induced uropathy literature).

9. **Contraindications**: Not formally established in published literature. Extrapolated from mechanism and case reports.

10. **Human dependence characterization**: No published human dependence case series, withdrawal report, or clinical addiction assessment for MXE.

11. **Discovery attribution**: The commonly cited attribution to a specific underground chemist (William Mathew Eibeck, 2006) could not be verified against peer-reviewed sources.

12. **Dopamine reuptake inhibition**: Cited as a pharmacological mechanism in multiple reviews and the seed data, but not confirmed by published binding assays (Roth 2013 PDSP screen covers DAT).

13. **Primary ROA**: The brief lists no confirmed primary ROA. The published literature documents insufflation, oral, and inhalation cases. Insufflation and oral appear to be the most common from case reports and survey data, but frequency data are not published.

14. **Physical properties completeness**: SMILES string not confirmed via PubChem API (CID 52911279 exists but SMILES not returned by tool). Should be verified from PubChem directly.