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ketamine, deschloroketamine, methoxetamine +3 moreketamine, deschloroketamine, methoxetamine, PCP, DXM, nitrous oxide show less
O-PCE
O-PCE (2-oxo-PCE, eticyclidone) is a synthetic dissociative of the arylcyclohexylamine class. It is a close structural relative of ketamine, more potent by weight and longer-lasting.[1] It blocks glutamate signaling in the brain, producing deep dissociation — detachment from body, environment, and sense of self.
O-PCE is an emerging synthetic dissociative of the arylcyclohexylamine class. It is a close structural relative of ketamine, more potent by weight and longer-lasting.[1] O-PCE is a presumed NMDA receptor antagonist, producing its effects by blocking glutamate signaling at the brain's primary excitatory ion channel.[2]
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O-PCE appeared on research chemical markets around 2016, with initial detections in France.[2] Within months of clinical detection in Hong Kong, a cluster of 56 poisonings established its profile — many victims believed they had purchased ketamine.[3] It circulates on unregulated markets today and is controlled in the UK, Germany, Sweden, China, and Hong Kong.
Subjective effects include dissociation, depersonalization, derealization, analgesia, amnesia, and pronounced motor impairment. The experience is heavier and more enveloping than ketamine — a deep cognitive detachment that feels immersive and difficult to navigate.[2] Confusion, disorientation, and agitation are common unwanted outcomes.
No lethal dose has been established, and no dependence studies exist, but O-PCE's acute toxicity is more severe than ketamine's — a 16% seizure rate in acute poisonings sets it apart.[3] One fatality involved combining it with the antidepressant venlafaxine,[4] and CNS depressants add respiratory depression risk. The entire evidence base is forensic case reports and metabolite studies — no controlled human research exists.[5]
History[edit]
Discovery and emergence
O-PCE appeared on research chemical markets around 2016, with initial detections in France.[2] Claims that it was synthesized during 1960s pharmaceutical research at Parke-Davis almost certainly confuse it with PCE (eticyclidine), a structurally distinct compound.[2] No verified primary source links O-PCE to that program. citation needed
Clinical detection
The first confirmed detections came from Hong Kong in late 2017, where seized samples were physically indistinguishable from ketamine.[6] A cluster of 56 acute poisonings followed, many involving users who thought they had purchased ketamine.[3] The earliest peer-reviewed clinical report appeared in December 2017.[7]
Fatality and forensic characterization
The one published fatality, reported in 2019, involved a 52-year-old man who had combined O-PCE with venlafaxine.[4] Germany brought O-PCE under formal control the same year.[2] From 2021 onward, forensic researchers identified its metabolites and estimated an half-life of around 5 hours.[5][8][9]
The name O-PCE abbreviates "2-Oxo-Phenylcyclohexylethylamine," distinguishing it from PCE by its ketone group. In forensic literature it also appears as deschloro-N-ethyl-ketamine.[10] Its reputation in research chemical communities centers on higher potency and longer duration than ketamine, and its frequent appearance as an undisclosed ketamine substitute.[6]
Chemistry[edit]
Structural class
O-PCE belongs to the arylcyclohexylamine chemical class, specifically the β-keto subtype that also includes ketamine and deschloroketamine.[11]
It differs from ketamine by two structural changes: the chlorine on the phenyl ring is absent, and the N-methyl group is replaced with an N-ethyl group.[1] Its molecular formula is C₁₄H₁₉NO (molecular weight 217.31 g/mol).[11]
Pharmacology[edit]
Mechanism of action
No receptor binding studies have been done for O-PCE. Based on its chemical class, it is presumed to block the brain's NMDA — the main channel for glutamate signaling, involved in learning, memory, and sensory processing. This mechanism is confirmed for structurally related compounds.[12][1]
Pharmacokinetics
The only published half-life estimate is approximately 5 hours, derived from a single multidrug exposure case.[9] O-PCE is extensively metabolized — the parent compound is undetectable in urine, and detection requires testing for specific metabolites.[5][8]
Cardiovascular effects
Blood pressure elevation (80%) and tachycardia (40%) were documented in 56 acute poisoning cases.[3] This results from NMDA blockade reducing the brain's inhibitory control over the sympathetic nervous system.[13]
Neuroscience[edit]
Where it acts
NMDA blockade disconnects the cortex from deeper brain structures — the neural basis of dissociation. At sub-anesthetic doses, it preferentially affects inhibitory cells, which paradoxically increases cortical activity.[13]
This disinhibition explains both the subjective sense of detachment and the elevated blood pressure and heart rate seen in O-PCE poisonings.[3]
Why it matters
NMDA receptors help the brain compare what it expects to sense against what it actually senses. When they are blocked, that process breaks down — producing unrealness, perceptual distortion, and at its most intense, complete dissolution of the sense of self.
The 16% convulsion rate documented for O-PCE[3] is unexplained. Ketamine has anticonvulsant properties, so seizures in a structurally similar compound raise questions about greater cortical disinhibition, altered receptor selectivity from the missing chloro group, or unmeasured off-target activity. O-PCE's actual binding profile, and whether its two enantiomers differ in potency, remains entirely unmeasured.
Subjective Effects[edit]
O-PCE produces a deep, enveloping dissociation that strips away physical sensation and environmental awareness — and at its most intense, the sense of having a self. The detachment is heavy and immersive — a sense of being pulled inward, away from body and surroundings, rather than floating above them.
Within the arylcyclohexylamine class, O-PCE sits between ketamine and methoxetamine in both depth and duration. It is heavier and longer-lasting than ketamine, with a qualitative depth and prolonged aftereffect profile closer to methoxetamine.
O-PCE appeared on research chemical markets around 2016, with the first peer-reviewed report published from Hong Kong in December 2017.[3] A cluster of 56 poisonings soon followed — many involving users who believed they had purchased ketamine — establishing the compound's clinical profile and revealing its elevated potency.[4] It circulates in powder and crystalline forms on unregulated markets and is controlled in several jurisdictions including the UK, Germany, and China.
Subjective effects include dissociation, depersonalization, derealization, analgesia, and amnesia. The experience is described as heavier and more immersive than ketamine — a deep, enveloping cognitive detachment with pronounced motor impairment and a lingering aftereffect window.[5] Confusion, disorientation, and agitation are common unsought effects.
No dependence studies exist, but cross-tolerance with other NMDA antagonists is expected; the toxic dose in humans is unknown. One published fatality involved co-ingestion with venlafaxine,[6] and acute poisonings feature convulsions (16%), elevated blood pressure, and rapid heart rate — a profile notably more severe than ketamine's.[4] No controlled human studies have been conducted; the entire evidence base consists of forensic case reports and in vitro metabolic profiling.[7][8]
History[edit]
Discovery and emergence
O-PCE appeared on research chemical markets around 2016, with initial detection reportedly occurring in France.[5] A secondary source claims synthesis during pharmaceutical research at Parke-Davis in 1962, but this almost certainly conflates O-PCE with PCE (eticyclidine), a structurally distinct compound lacking the 2-oxo group that defines the arylcyclohexanone subclass.[5] No verified primary source establishes O-PCE as a product of that program. citation needed
Clinical detection
The earliest confirmed detections occurred in Hong Kong in October 2017, where seized samples appeared as powdery or crystalline solids largely indistinguishable from ketamine — approximately 69% contained O-PCE as the sole active substance.[9] Between October and November 2017, a cluster of 56 acute poisoning cases established O-PCE's clinical profile, with many users unaware they had ingested a compound more potent than the ketamine they intended to purchase.[4] The earliest peer-reviewed clinical report was published in December 2017.[3]
Fatality and forensic characterization
The sole published fatality, reported in 2019, involved a 52-year-old male who had co-ingested O-PCE and venlafaxine.[6] Germany brought O-PCE under formal control the same year via the Neue-psychoaktive-Stoffe-Gesetz.[5] From 2021 onward, forensic metabolic profiling advanced substantially: Larabi and colleagues identified 15 metabolites,[7] Xu and colleagues recommended hydroxy-O-PCE as a forensic biomarker,[10] and Magny and colleagues annotated 27 metabolites and estimated an half-life of approximately 5 hours.[8]
The name O-PCE abbreviates "2-Oxo-Phenylcyclohexylethylamine," referencing the ketone (oxo) group that distinguishes it from PCE (eticyclidine). The alternate name eticyclidone follows IUPAC-adjacent nomenclature for cyclic ketones. In forensic literature, the compound also appears as deschloro-N-ethyl-ketamine,[11] a systematic name describing its structural relationship to ketamine.
Chemistry[edit]
Structural class
O-PCE belongs to the arylcyclohexylamine chemical class, specifically the β-keto (arylcyclohexanone) subtype characterized by a ketone at the 2-position of the cyclohexane ring.[12] This ketone is the structural feature shared with ketamine and deschloroketamine.
O-PCE differs from ketamine by two modifications: the 2-chloro group is removed from the phenyl ring, and the N-methyl group is replaced with an N-ethyl group.[1] It shares the same N-ethylaminocyclohexanone core as methoxetamine, differing only in the absence of a 3-methoxy substituent on the phenyl ring.[1]
Molecular identity
| Molecular formula | C₁₄H₁₉NO |
| Molecular weight | 217.31 g/mol |
The molecule consists of a cyclohexanone ring with a phenyl group and an ethylamino group at the 2-position, creating an α-amino ketone arrangement characteristic of the β-keto arylcyclohexylamine subclass.[12]
Stereochemistry
O-PCE possesses one chirality center at C-2, generating R and S enantiomers. No published studies have examined the enantiomeric pharmacology of O-PCE.
By analogy with ketamine — where the S-(+)-enantiomer shows approximately 3–4-fold higher NMDA affinity than the R-(−)-enantiomer — enantioselective differences in potency are plausible but uncharacterized. citation needed All available forensic and market samples appear to be racemic mixtures.
Physical properties
Seized samples appear as powdery or crystalline solids,[11] with certain preparations described as having a reddish coloration.[9] No standardized physical chemistry data — melting point, solubility, or pKa — have been published.
The compound is physically indistinguishable from ketamine in seized samples, complicating field identification.[9]
Pharmacology[edit]
Mechanism of action
No receptor binding studies have been published for O-PCE. All pharmacological characterization rests on structural analogy and class-level data.
As a β-keto arylcyclohexylamine, O-PCE is presumed to act by blocking the NMDA receptor — the brain's primary excitatory ion channel involved in learning, memory, and sensory processing. The compound enters the open channel and lodges at the phencyclidine binding site, preventing calcium flow and disrupting normal glutamate signaling. This mechanism is well-established for the arylcyclohexylamine class: binding data for structurally related compounds including methoxetamine and PCE analogs confirm high-affinity NMDA binding.[2][1] safety citation needed
Sigma receptor binding is plausible based on class data — related compounds show appreciable sigma affinity, though this is less prominent for ketamine-type analogs with the N-alkylaminocyclohexanone core.[2][13] Claims of μ-opioid activity appear in some secondary sources but lack substance-specific support and should be considered unverified. inferred
Pharmacokinetics
The only published half-life estimate for O-PCE is approximately 5 hours, derived from a single multidrug exposure case.[8]
O-PCE is extensively metabolized. Larabi and colleagues identified 15 metabolites through liver microsome and biological specimen analysis,[7] Xu and colleagues confirmed metabolism in zebrafish and human liver microsomes and recommended hydroxy-O-PCE as a forensic biomarker,[10] and Magny and colleagues annotated 27 metabolites in the most detailed in vivo characterization to date.[8] The parent compound is undetectable in urine after metabolism; detection requires testing for specific metabolites.[7]
Oral bioavailability has not been measured. The substantially slower onset by oral administration compared with insufflation[5] is consistent with significant first-pass metabolism, as observed for ketamine (oral bioavailability approximately 17–29%).[14]
Cardiovascular effects
Acute poisoning data demonstrate pronounced sympathomimetic activation: blood pressure elevation in 80% and tachycardia in 40% of 56 presentations.[4] These effects are consistent with NMDA antagonism reducing inhibitory tone on the sympathetic nervous system.[15]
Neuroscience[edit]
Where it acts
No neuroimaging or electrophysiology studies have been conducted with O-PCE. Based on ketamine research, NMDA blockade by arylcyclohexylamines produces cortical-subcortical disconnection — the neural basis of dissociative experience. At sub-anesthetic doses, the blockade preferentially affects inhibitory interneurons, releasing excitatory neurons from their normal restraint and producing a paradoxical increase in cortical activity.[15]
This disinhibition accounts for both the subjective sense of detachment and the sympathomimetic effects — elevated blood pressure and heart rate — documented in O-PCE poisoning cases.[4]
Why it matters
NMDA receptors are central to how the brain compares expectations against incoming sensory data. When these receptors are blocked, the brain's ability to weight and update its predictions degrades — producing the characteristic sense of unrealness, perceptual distortion, and at higher doses, complete dissolution of the sense of self.
Separately, ketamine research has revealed that NMDA blockade can trigger rapid formation of new neural connections, a mechanism underlying ketamine's antidepressant action. Whether O-PCE engages this same neuroplasticity pathway is unknown.
The elevated convulsion rate (16%) observed with O-PCE[4] is unexplained. Ketamine possesses anticonvulsant properties, so convulsions in a structurally similar compound demand explanation — whether from greater cortical disinhibition at equivalent doses, altered receptor selectivity from the missing chloro group, or off-target activity not shared with ketamine.
Subjective Effects[edit]
O-PCE produces a deep, immersive dissociative state that users consistently describe as heavier and more enveloping than ketamine. At lower doses, mild cognitive detachment and perceptual softening predominate; higher doses progress through pronounced depersonalization and derealization toward complete disconnection from body and environment. Set and setting strongly influence whether this detachment registers as exploratory or disorienting — psychological preparation and environment can substantially shape the character of the experience.
Within the arylcyclohexylamine class, O-PCE sits between ketamine and methoxetamine in both duration and character: more potent by weight and longer-lasting than ketamine, with an aftereffect profile and qualitative depth closer to MXE. The elevated convulsion rate in clinical data[4] marks a meaningful safety distinction from ketamine's comparatively benign acute toxicity.
Effect Grid
At common doses, the full dissociative experience manifests: pronounced depersonalization and derealization, significant spatial and temporal distortion, analgesia, and a characteristic sense of detachment from the body and environment. Thought patterns become nonlinear, with cognitive distortions and memory suppression becoming prominent. Visual disturbances include altered depth perception and mild closed-eye imagery.
Physically, blood pressure and heart rate elevation become more apparent. Motor control is significantly impaired — walking becomes uncoordinated and fine motor tasks are difficult. Nausea may occur, particularly with oral administration.
The experience demands 4–6 hours of uninterrupted time. Sleep is unlikely during the active phase, and aftereffects may impair concentration and coordination for 6–24 hours.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Depth perception distortion · Vestibular distortion · Proprioceptive distortion · Visual haze / noise · Sleep-transition hallucinations · Music enhancement · Auditory distortion · After-images · Auditory enhancement · Auditory misinterpretation · Auditory suppression · Brightness alteration · Color alteration · Environmental patterning · Ganzfeld effect · Holotropic state · Peripheral vision distortion · Sensory deprivation · Tracers · Visual drifting · Color enhancement · Color suppression · Dreaming suppression · Geometry · Peripheral misidentification · Symmetrical texture repetition · Taste suppression · Tinnitus · Touch enhancement · Visual diffraction · Visual morphing · Synesthesia · Visual breathing · Visual magnification · Visual melting · Visual processing suppression · Internal hallucinations · Environmental orbism / cubism · Visual scenery slicing · Auditory hallucinations · External hallucinations · Object transformations · Perspective hallucinations · Object activation · Visual flipping · Visual recursion
Sleep-transition hallucinations · Music enhancement · Auditory distortion · After-images · Auditory enhancement · Auditory misinterpretation · Auditory suppression · Brightness alteration · Color alteration · Environmental patterning · Ganzfeld effect · Holotropic state · Peripheral vision distortion · Sensory deprivation · Tracers · Visual drifting · Color enhancement · Color suppression · Dreaming suppression · Geometry · Peripheral misidentification · Symmetrical texture repetition · Taste suppression · Tinnitus · Touch enhancement · Visual diffraction · Visual morphing · Synesthesia · Visual breathing · Visual magnification · Visual melting · Visual processing suppression · Internal hallucinations · Environmental orbism / cubism · Visual scenery slicing · Auditory hallucinations · External hallucinations · Object transformations · Perspective hallucinations · Object activation · Visual flipping · Visual recursion
Dizziness · Bodily lightness · Body schema distortion · Physical fatigue · Sedation · Tactile euphoria · Spontaneous body sensations · Insomnia · Laughter fits · Muscle relaxation · Sexual arousal suppression · Nausea · Breathing alteration · Headache · Heart rate perception changes · Nasal congestion · Pupil dilation · Stimulation · Tingling / electric sensations · Vasoconstriction · Vibrations / buzzing · Bodily pressures · Dry mouth · Excessive sweating · Restlessness · Trembling · Wakefulness · Abnormal heartbeat · Involuntary body movements · Vomiting · Yawning · Bodily dissociation · Phantom limb sensations · Tactile hallucination
Physical fatigue · Sedation · Tactile euphoria · Spontaneous body sensations · Insomnia · Laughter fits · Muscle relaxation · Sexual arousal suppression · Nausea · Breathing alteration · Headache · Heart rate perception changes · Nasal congestion · Pupil dilation · Stimulation · Tingling / electric sensations · Vibrations / buzzing · Bodily pressures · Dry mouth · Excessive sweating · Restlessness · Trembling · Wakefulness · Abnormal heartbeat · Involuntary body movements · Vomiting · Yawning · Bodily dissociation · Phantom limb sensations · Tactile hallucination
Confusion · Focus suppression · Information processing suppression · Thought disorganization · Immersion enhancement · Analysis suppression · Introspection enhancement · Thought deceleration · Cognitive fatigue · Memory fragmentation · Pattern recognition suppression · Conceptual thinking · Aesthetic enhancement · Language suppression · Motivation suppression · Openness enhancement · Suggestibility enhancement · Thought loops · Creativity enhancement · Humor enhancement · Cognitive flexibility · Delusions of sobriety · Multiple thought streams · Novelty enhancement · Thought connectivity · Cognitive dysphoria · Memory replays · Synchronicity · Thought acceleration · Amnesia · Delirium · Delusions
Thought disorganization · Immersion enhancement · Analysis suppression · Introspection enhancement · Thought deceleration · Cognitive fatigue · Memory fragmentation · Pattern recognition suppression · Conceptual thinking · Aesthetic enhancement · Language suppression · Motivation suppression · Openness enhancement · Thought loops · Creativity enhancement · Humor enhancement · Cognitive flexibility · Delusions of sobriety · Multiple thought streams · Novelty enhancement · Thought connectivity · Cognitive dysphoria · Memory replays · Synchronicity · Thought acceleration · Amnesia · Delirium · Delusions
Empathy suppression · Anhedonia · Anxiety · Emotional enhancement · Emotional lability · Irritability · Simultaneous emotions · Catharsis · Dysphoria · Mania
Emotional enhancement · Emotional lability · Irritability · Simultaneous emotions · Catharsis · Dysphoria
Disinhibition · Communication suppression · Craving · Sociability suppression · Automaticity · Emotional susceptibility · Flow state · Sociability enhancement · Social connection · Trust enhancement · Cognitive disconnection · Ego dissolution · Boundary dissolution · Identity alteration
Automaticity · Emotional susceptibility · Flow state · Sociability enhancement · Social connection · Trust enhancement · Cognitive disconnection · Ego dissolution · Boundary dissolution · Identity alteration
Time cessation
Cessation · Death-rebirth sequence · Entity contact · Near-death experience · Non-dual awareness · Transpersonal visions
Non-dual awareness · Transpersonal visions
Timeline
First effects appear 20–40 minutes after oral ingestion: a gradual shift in mental state, subtle bodily lightness, and the first hints of dissociative detachment. The slower onset reflects significant first-pass hepatic metabolism.
Dissociative effects develop progressively. Spatial perception shifts, motor coordination declines, and a growing sense of detachment from the body and surroundings emerges. Nausea is more common by this route than by insufflation.
Maximum dissociation is reached: depersonalization, derealization, analgesia, pronounced motor impairment, and significant memory suppression. The oral peak tends to be longer and more gradual than the insufflated peak. Cardiovascular stimulation is present.
Effects slowly diminish from peak intensity. Dissociative qualities persist but become less immersive. Cognitive function returns gradually.
Dissociation fades into residual cognitive fog and mild depersonalization. Emotional processing may feel dampened or altered. Physical coordination improves but remains impaired.
Residual effects include cognitive cloudiness, mood alterations, subtle dissociative symptoms, and disrupted sleep. The aftereffect window for oral O-PCE is notably extended, with some reports describing lingering effects up to 48 hours.
⚠ Avoid driving or operating machinery for at least 24 hours after oral administration, as subclinical dissociative impairment may persist far beyond the subjective experience.
Safety[edit]
- Acute toxicity
- Moderate
- Chronic toxicity
- Moderate
- Withdrawal
- None
- Tolerance buildup
- moderate
- Tolerance reset
- 14 days
- Physical
- Low
- Psychological
- Moderate
- Compulsive redosing
- Moderate
- Dose escalation
- Moderate
- Cross-tol.
- ketamine · deschloroketamine · methoxetamine
Toxicity
Acute toxicity
The main toxicity data come from 56 poisoning cases in Hong Kong.[3] The most common presentations were impaired consciousness (84%), elevated blood pressure (80%), confusion (60%), abnormal behavior (44%), rapid heart rate (40%), and convulsions (16%). Three patients required intensive care; all recovered.
The convulsion rate is significantly higher than in ketamine poisonings and is a key safety distinction.[3]
Standard ketamine urine drug screens do not detect O-PCE.[3] A negative ketamine test cannot rule out arylcyclohexylamine exposure. Laboratory confirmation requires advanced analytical methods such as LC-MS/MS or GC-HRMS.[6][14]
Fatality data
One published fatality directly involved O-PCE: a 52-year-old man who co-ingested O-PCE and venlafaxine, with deschloroketamine also detected.[4] Postmortem blood concentration was approximately 1.2 µg/mL,[4][2] compared to 0.08–0.31 µg/mL in non-fatal cases.[6]
Forensic literature suggests additional fatalities may exist in unpublished databases.[5] A fatal polydrug case involving related compounds 2F-DCK and 3-MeO-PCE was attributed to breathing failure.[15]
Cardiovascular effects
Blood pressure elevation (80%) and rapid heart rate (40%) were prominent in the poisoning series.[3] NMDA blockade reduces the brain's inhibitory control over the sympathetic nervous system, driving this cardiovascular activation.[13]
Psychological Risks
No controlled studies on psychological risks exist. Acute risks by analogy with the dissociative class include disorientation, agitation, anxiety, paranoia, and psychotic-like symptoms. The Hong Kong cases documented confusion in 60% and abnormal behavior in 44%.[3]
Aftershocks can persist up to 48 hours by the oral route,[2] extending the window of psychological vulnerability. Depersonalization and derealization may distress unprepared users or persist beyond the acute phase.
Tolerance & Dependence
No substance-specific tolerance or dependence studies exist. Community sources estimate tolerance half-life at 3–7 days with full reset in 1–2 weeks.[2] Cross-tolerance among NMDA antagonists is established in animal models,[16] and O-PCE is expected to share it with ketamine, PCP, MXE, and DXM.
O-PCE appears in multi-drug chronic use patterns including chemsex contexts,[9] suggesting potential for compulsive redosing. No published case of O-PCE-specific dependence or withdrawal has been identified.
Drug Interactions
Published interactions
Venlafaxine (SNRI): Co-ingestion caused the only published O-PCE fatality.[4] The mechanism is uncharacterized but may involve combined CNS depression, serotonin effects, or cardiovascular synergy. safety citation needed
GHB: Combined exposure with O-PCE, 3-MMC, and MXE resulted in loss of consciousness and intensive care admission.[9]
CNS depressant combinations
Opioids, alcohol, benzodiazepines, and GHB add sedation and breathing suppression risk when combined with NMDA antagonists. A fatal polydrug case involving related compounds 2F-DCK and 3-MeO-PCE was attributed to respiratory depression.[15]
MAOIs
Monoamine oxidase inhibitors are contraindicated with dissociative NMDA antagonists. Combining them raises serotonin to dangerous levels and can spike blood pressure severely, though this interaction has not been verified specifically for O-PCE. safety citation needed
Enzyme-mediated interactions (inferred)
Drugs that inhibit or induce the liver enzymes responsible for O-PCE metabolism (CYP2B6 and CYP3A4, inferred from ketamine and MXE data[17]) may increase or decrease O-PCE blood levels. No O-PCE-specific interaction studies exist. inferred
Contraindications
8 knownNo substance-specific contraindication data exist. The following are inferred from pharmacological class and published clinical data:
Heart conditions: Blood pressure elevation (80%) and rapid heart rate (40%)[3] make pre-existing cardiovascular conditions a relative contraindication, consistent with ketamine's established cardiovascular risk.[13]
Seizure disorders: The 16% convulsion rate[3] suggests O-PCE may lower the seizure threshold.
Concurrent SNRI/SSRI use: The fatal interaction with venlafaxine[4] warrants listing SNRIs as a relative contraindication pending mechanistic characterization.
Concurrent MAOI use: Contraindicated by class-level evidence for dangerous serotonin overload and blood pressure elevation. inferred
Concurrent CNS depressants: Alcohol, opioids, benzodiazepines, and GHB carry additive sedation and breathing suppression risk.[15][9]
Psychotic disorders and severe psychiatric conditions: Class-level contraindication for all dissociative NMDA antagonists due to potential for psychotic symptom precipitation. inferred
Harm Reduction[edit]
Forms & Identification
O-PCE is a white to off-white powder or crystalline solid physically indistinguishable from ketamine.[6] The Hong Kong poisoning cluster showed that users frequently received O-PCE when they believed they had purchased ketamine.[3]
Because O-PCE is more potent by weight, dosing at ketamine-calibrated amounts produces disproportionately intense and potentially dangerous effects.
Standard ketamine immunoassay strips will not detect O-PCE.[3] Reagent testing can distinguish arylcyclohexylamines from other drug classes but cannot reliably tell O-PCE from ketamine or deschloroketamine. Mass spectrometry via a drug checking service is the only reliable identification method.
Guidelines
- Test every batch. O-PCE looks identical to ketamine. Use reagent testing as a first screen and drug checking services where available.
- Weigh doses precisely. O-PCE is more potent by weight than ketamine. A milligram-precision scale is essential. Do not eyeball powder.
- Start low, redose slowly. Oral onset can take 20–40 minutes.[2] Do not redose before full onset — stacking doses is a primary cause of unexpectedly intense experiences.
- Avoid combinations. The published fatality involved co-ingestion with venlafaxine.[4] CNS depressants — alcohol, opioids, benzodiazepines, GHB — carry additive respiratory risk.[15]
- Stay seated or lying down. Motor impairment and disorientation are prominent. Attempting to walk during peak effects risks injury.
- Keep the airway clear. Nausea is possible. If lying down, use the recovery position to prevent aspiration.
Set & Setting
O-PCE dissociation is deep and immersive. Motor impairment is pronounced — falls, collisions, and spatial confusion are realistic risks at common doses. A ground-level, hazard-free environment away from stairs, water, traffic, and sharp objects is essential.
A sober, trusted sitter is strongly recommended, particularly at doses approaching or exceeding common thresholds. The extended aftereffect window means impairment may persist well beyond the main experience — plan for a full day without obligations.
Aftercare & integration. O-PCE's aftereffect window can extend well beyond the acute experience — up to 48 hours by the oral route.[2] Residual dissociation, cognitive blunting, and emotional flatness are common during this period.
Grounding practices — physical contact with textured surfaces, cold water on the face, focused breathing, familiar music — can help re-establish a sense of embodied presence.
Avoid driving, operating machinery, or making significant decisions until the aftereffect period has fully resolved. Sleep, hydration, and gentle physical movement support recovery. If depersonalization or derealization persist beyond 72 hours, seek professional support from a clinician familiar with substance-related dissociative experiences.
Recovery & Support
O-PCE appears in multi-drug chronic use patterns, including chemsex contexts.[9] If use has become compulsive or difficult to control, support is available.
SAMHSA's National Helpline (1-800-662-4357) provides free referrals in the United States. The Fireside Project (62-FIRESIDE) offers peer support for psychoactive substance experiences. Online communities focused on dissociative harm reduction can provide non-judgmental information and peer connection.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Seizures, loss of consciousness that does not respond to loud voice and firm shoulder contact, slow or irregular breathing, chest pain, or sustained agitation with self-harm risk all require immediate medical attention. The 16% convulsion rate documented for O-PCE[3] means seizures are a realistic possibility.
Immediate steps:
- 1. Call emergency services.
- 2. Place the person in the recovery position if unconscious but breathing.
- 3. Do not restrain a person having a seizure — clear the area of objects they could strike and protect their head.
- 4. Do not attempt to induce vomiting.
- 5. Monitor breathing continuously while waiting for help.
What to tell the dispatcher: Name the substance (O-PCE, a dissociative similar to ketamine), approximate amount and time of ingestion, route of administration, and current symptoms. Mention any other substances taken. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
Note: Standard ketamine urine tests will not detect O-PCE.[3] Inform medical staff that the substance is an arylcyclohexylamine not detected by standard immunoassay screens.
Legal Status[edit]
O-PCE is not subject to international drug control conventions as of April 2026,[2] but several countries have enacted specific or generic controls.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United Kingdom | Class B controlled substance | Covered under the generic arylcyclohexylamine clause (S.I. 2013/239), effective February 26, 2013. Also prohibited under the Psychoactive Substances Act 2016 (supply offense).[2] |
| Germany | Controlled under NpSG | Regulated under the Neue-psychoaktive-Stoffe-Gesetz, effective July 18, 2019.[2] |
| Sweden | Banned | Explicitly scheduled.[2] |
| China | Controlled | Classified under narcotics regulations.[2] |
| Hong Kong | Banned | Explicitly controlled; enforcement documented in seizure data.[6][2] |
| United States | Not explicitly scheduled | Not listed on the DEA Controlled Substances Schedule. The Federal Analogue Act (21 U.S.C. § 813) may apply if intended for human consumption and substantially similar to a Schedule I/II substance. O-PCE is a plausible analog of ketamine (Schedule III) or PCP (Schedule II). Legal risk is prosecution-context dependent.[2] |
| Canada | Not explicitly scheduled | Monitored as NPS under the CDSA framework but not formally listed in controlled substance schedules as of research date.[2] |
| Australia | Status unclear | No specific entry found in the Therapeutic Goods (Poisons Standard) instruments through 2025. May be captured under broad analog provisions in state/territory law. citation needed |
Legal status varies by jurisdiction and changes without notice. This is not legal advice — verify current status through official national sources before making decisions.
Safety[edit]
- Acute toxicity
- Moderate
- Chronic toxicity
- Moderate
- Withdrawal
- None
- Tolerance buildup
- moderate
- Tolerance reset
- 14 days
- Physical
- Low
- Psychological
- Moderate
- Compulsive redosing
- Moderate
- Dose escalation
- Moderate
- Cross-tol.
- ketamine · deschloroketamine · methoxetamine
Toxicity
No controlled toxicity studies have been conducted and no lethal dose has been established in any species. The exact dose that produces life-threatening effects in humans is unknown.
Acute toxicity
The primary toxicity data come from 56 poisoning cases documented in Hong Kong.[4] The most common presentations included impaired consciousness (84%), elevated blood pressure (80%), confusion (60%), abnormal behavior (44%), rapid heart rate (40%), and convulsions (16%). Three patients required intensive care; all recovered with supportive management.
The convulsion rate is significantly elevated compared to ketamine poisonings and represents a distinguishing safety concern for O-PCE.[4]
Standard ketamine urine drug screens do not detect O-PCE.[4] A negative ketamine test cannot rule out arylcyclohexylamine exposure. Laboratory confirmation requires advanced analytical methods such as LC-MS/MS or GC-HRMS.[9][16]
Fatality data
One published fatality directly involved O-PCE: a 52-year-old male who co-ingested O-PCE and venlafaxine, with deschloroketamine also detected.[6] Postmortem blood concentration was approximately 1.2 µg/mL,[6][5] compared to non-fatal blood concentrations of 0.08–0.31 µg/mL in impaired driving cases.[9]
Forensic literature suggests additional fatalities may exist in databases not yet published in peer-reviewed journals.[7] A fatal polydrug case involving the closely related compounds 2F-DCK and 3-MeO-PCE was attributed to respiratory depression.[17]
Cardiovascular effects
Elevated blood pressure (80%) and rapid heart rate (40%) were prominent in the poisoning case series.[4] These effects result from NMDA antagonism reducing the brain's inhibitory control over sympathetic nervous system activation.[15] No data on chronic cardiovascular toxicity exist.
Psychological Risks
No controlled studies have evaluated psychological risks. By analogy with the dissociative class, acute risks include disorientation, agitation, anxiety, paranoia, and psychotic-like symptoms. The Hong Kong case series documented confusion in 60% and abnormal behavior in 44% of presentations.[4]
Aftershocks persisting up to 48 hours by the oral route[5] may extend the window of psychological vulnerability. Depersonalization and derealization may produce distress in unprepared individuals or persist beyond the acute phase. No data on persistent perceptual changes or chronic psychological effects specific to O-PCE have been published.
Tolerance & Dependence
No substance-specific tolerance or dependence studies exist. Community sources estimate tolerance half-life at 3–7 days with full reset in 1–2 weeks.[5]
Cross-tolerance among NMDA receptor blockers is established in animal models.[18] O-PCE is expected to share cross-tolerance with ketamine, PCP, MXE, DXM, and other NMDA antagonists.
The compound appears in chemsex contexts with multi-drug chronic use patterns,[8] suggesting potential for psychological reinforcement and compulsive redosing, though no published case of O-PCE-specific dependence or withdrawal has been identified.
Drug Interactions
Published interactions
Venlafaxine (SNRI): Co-ingestion resulted in the only published O-PCE fatality.[6] The mechanism is uncharacterized but may involve additive central nervous system depression, serotonin-related interaction, or cardiovascular synergy. safety citation needed
GHB: Combined exposure with O-PCE, 3-MMC, and MXE resulted in loss of consciousness and intensive care admission.[8]
CNS depressant combinations
Opioids, alcohol, benzodiazepines, and GHB carry additive sedation and breathing suppression risk when combined with NMDA antagonists. A fatal polydrug case involving the related compounds 2F-DCK and 3-MeO-PCE was attributed to respiratory depression.[17]
MAOIs
Monoamine oxidase inhibitors are contraindicated with the dissociative NMDA antagonist class due to risk of serotonin syndrome and dangerous blood pressure elevation, though this interaction has not been verified specifically for O-PCE. safety citation needed
Enzyme-mediated interactions (inferred)
Drugs that inhibit or induce the liver enzymes likely responsible for O-PCE metabolism (CYP2B6 and CYP3A4, inferred from ketamine and MXE data[19]) may increase or decrease O-PCE blood levels. No O-PCE-specific interaction studies exist. inferred
Contraindications
8 knownNo substance-specific contraindication data exist. The following are inferred from pharmacological class and published clinical data:
Heart conditions: The high prevalence of blood pressure elevation (80%) and rapid heart rate (40%)[4] makes pre-existing cardiovascular conditions a relative contraindication, consistent with ketamine's established cardiovascular risk profile.[15]
Seizure disorders: The 16% convulsion rate[4] suggests O-PCE may lower the seizure threshold.
Concurrent SNRI/SSRI use: The fatal interaction with venlafaxine[6] warrants listing serotonin-norepinephrine reuptake inhibitors as a relative contraindication pending mechanistic characterization.
Concurrent MAOI use: Contraindicated by class-level evidence for serotonin syndrome and dangerous blood pressure elevation. inferred
Concurrent CNS depressants: Alcohol, opioids, benzodiazepines, and GHB carry additive sedation and breathing suppression risk.[17][8]
Psychotic disorders and severe psychiatric conditions: Class-level contraindication for all dissociative NMDA antagonists due to potential for psychotic symptom precipitation. inferred
Harm Reduction[edit]
Forms & Identification
O-PCE circulates as a white to off-white powder or crystalline solid that is physically indistinguishable from ketamine.[9] This visual similarity is the compound's central identification challenge — the Hong Kong poisoning cluster demonstrated that users frequently received O-PCE when they believed they had purchased ketamine.[4] Because O-PCE is significantly more potent by weight, dosing at ketamine-calibrated amounts produces disproportionately intense and potentially dangerous effects.
Standard ketamine immunoassay strips will not detect O-PCE.[4] Reagent testing can help distinguish arylcyclohexylamines from other substance classes but cannot reliably differentiate O-PCE from ketamine or deschloroketamine. Quantitative analysis via a drug checking service with mass spectrometry capability is the only reliable identification method.
Guidelines
- Test every batch. Visual inspection cannot distinguish O-PCE from ketamine or other arylcyclohexylamines. Use reagent testing as a first screen and drug checking services where available.
- Weigh doses precisely. O-PCE is more potent by weight than ketamine. Volumetric dosing or eyeballing powder significantly increases overdose risk. A milligram-precision scale is essential.
- Start low, redose slowly. Oral onset can take 20–40 minutes.[5] Do not redose before full onset — stacking doses is a primary cause of unexpectedly intense experiences.
- Avoid combinations. The published fatality involved co-ingestion with venlafaxine.[6] CNS depressant combinations (alcohol, opioids, benzodiazepines, GHB) carry additive respiratory risk.[17]
- Stay seated or lying down. Motor impairment and spatial disorientation are prominent. Attempting to walk during peak effects risks injury.
- Keep the airway clear. Nausea is possible. If lying down, use the recovery position to prevent aspiration.
Set & Setting
The depth and immersiveness of O-PCE dissociation demand careful environmental preparation. Motor impairment is pronounced — falls, collisions, and inability to navigate physical space are realistic risks at common doses. A ground-level, uncluttered environment away from hazards (stairs, water, traffic, sharp objects) is essential.
A sober, trusted sitter is strongly recommended, particularly at doses approaching or exceeding common thresholds. The extended aftereffect window means cognitive and perceptual impairment may persist well beyond the main experience — plan for a full day without obligations.
Aftercare & integration. O-PCE's aftereffect window can extend well beyond the acute experience — up to 48 hours by the oral route.[5] During this period, residual dissociation, cognitive blunting, and emotional flatness are commonly reported. Grounding practices — physical contact with textured surfaces, cold water on the face, focused breathing, familiar music — can help re-establish a sense of embodied presence.
Avoid driving, operating machinery, or making significant decisions until the aftereffect period has fully resolved. Sleep, hydration, and gentle physical movement support recovery. If depersonalization or derealization persist beyond 72 hours, or if distressing psychological symptoms emerge, seek professional support from a clinician familiar with substance-related dissociative experiences.
Recovery & Support
O-PCE appears in multi-drug chronic use patterns, including chemsex contexts.[8] If use has become compulsive or difficult to control, support is available. SAMHSA's National Helpline (1-800-662-4357) provides free referrals in the United States. The Fireside Project (62-FIRESIDE) offers peer support for psychoactive substance experiences. Online communities focused on dissociative harm reduction can provide non-judgmental information and peer connection for those working to change their relationship with these substances.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Seizures, loss of consciousness that does not respond to loud voice and firm shoulder contact, breathing that becomes slow or irregular, chest pain, or sustained agitation with self-harm risk all require immediate medical attention. The 16% convulsion rate documented for O-PCE[4] means seizures are a realistic possibility.
Immediate steps:
- 1. Call emergency services.
- 2. Place the person in the recovery position if unconscious but breathing.
- 3. Do not restrain a person having a seizure — clear the area of objects they could strike and protect their head.
- 4. Do not attempt to induce vomiting.
- 5. Monitor breathing continuously while waiting for help.
What to tell the dispatcher: Name the substance (O-PCE, a dissociative similar to ketamine), approximate amount and time of ingestion, route of administration, and current symptoms. Mention any other substances taken. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
Note: Standard ketamine urine tests will not detect O-PCE.[4] Inform medical staff that the substance is an arylcyclohexylamine not detected by standard immunoassay screens.
Legal Status[edit]
O-PCE is not subject to international control under the United Nations Convention on Psychotropic Substances as of April 2026.[5] National scheduling varies considerably, with several jurisdictions having enacted specific or generic controls while others rely on structural analog provisions or have no explicit coverage.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United Kingdom | Class B controlled substance | Covered under the generic arylcyclohexylamine clause (S.I. 2013/239), effective February 26, 2013. Also prohibited under the Psychoactive Substances Act 2016 (supply offense).[5] |
| Germany | Controlled under NpSG | Regulated under the Neue-psychoaktive-Stoffe-Gesetz, effective July 18, 2019.[5] |
| Sweden | Banned | Explicitly scheduled.[5] |
| China | Controlled | Classified under narcotics regulations.[5] |
| Hong Kong | Banned | Explicitly controlled; enforcement documented in seizure data.[9][5] |
| United States | Not explicitly scheduled | Not listed on the DEA Controlled Substances Schedule. The Federal Analogue Act (21 U.S.C. § 813) may apply if intended for human consumption and substantially similar to a Schedule I/II substance. O-PCE is a plausible analog of ketamine (Schedule III) or PCP (Schedule II). Legal risk is prosecution-context dependent.[5] |
| Canada | Not explicitly scheduled | Monitored as NPS under the CDSA framework but not formally listed in controlled substance schedules as of research date.[5] |
| Australia | Status unclear | No specific entry found in the Therapeutic Goods (Poisons Standard) instruments through 2025. May be captured under broad analog provisions in state/territory law. citation needed |
The UK's generic arylcyclohexylamine clause (S.I. 2013/239), effective February 26, 2013, may represent the earliest formal scheduling applicable to O-PCE in any jurisdiction, predating its documented emergence on research chemical markets by approximately three years.
Frequently asked questions
What is O-PCE?
O-PCE is a synthetic dissociative of the arylcyclohexylamine class, structurally related to ketamine, emerging on research-chemical markets around 2016. It is a presumed NMDA receptor antagonist with no published binding affinity data.
How long does O-PCE last?
Total duration by route of administration — Insufflated: 3 – 5 hours; Oral: 3 – 6 hours. Ranges vary with dose and individual factors; see the duration table for onset, peak, and after-effect phases.
Where can I find dosage information for O-PCE?
Psychedex publishes a dosage table for O-PCE on this page covering these routes of administration: oral, insufflated. Dose values are presented only in that table, always alongside their route of administration.
What are dangerous combinations with O-PCE?
The highest-severity documented interactions for O-PCE: Benzodiazepines, Barbiturates (Lethal), GHB, Baclofen (Lethal), GHB, GBL (Lethal), Local anesthetics (Lethal), Alpha-2 adrenergic receptor antagonist (Dangerous). See the interactions section for the full list with mechanisms and severity levels.
Is O-PCE addictive?
Psychedex records tolerance and dependence data rather than a yes/no rating. Recorded tolerance indicators for O-PCE: tolerance builds moderate; full reset takes 14 days; cross-tolerance develops with ketamine, deschloroketamine, methoxetamine, PCP, DXM, nitrous oxide. See the article's dependence and safety sections for recorded dependence data.
experience reports
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First-person accounts of subjective effects, timing, and outcomes — submitted for harm reduction.
references
- [1] ^abcWallach J, Brandt SD (2018) 1,2-Diarylethylamine- and Ketamine-Based New Psychoactive Substances — Handbook of Experimental Pharmacology doi:10.1007/164_2018_148
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- [5] ^abcdLarabi IA, Zerizer F, Ameline A, Etting I, Joseph D, Kintz P, Alvarez JC (2021) Metabolic profiling of deschloro-N-ethyl-ketamine and identification of new target metabolites in urine and hair using human liver microsomes and high-resolution accurate mass spectrometry — Drug Testing and Analysis doi:10.1002/dta.3007
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references
- [1] ^abcdWallach J, Brandt SD (2018) 1,2-Diarylethylamine- and Ketamine-Based New Psychoactive Substances — Handbook of Experimental Pharmacology doi:10.1007/164_2018_148
- [2] ^abcRoth BL, Gibbons S, Arunotayanun W, Huang XP, Setola V, Treble R, Iversen L (2013) The ketamine analogue methoxetamine and 3- and 4-methoxy analogues of phencyclidine are high affinity and selective ligands for the glutamate NMDA receptor — PLoS ONE doi:10.1371/journal.pone.0059334
- [3] ^abChong YK, Tang MH, Chan CL, Li YK, Ching CK, Mak TW (2017) 2-oxo-PCE: ketamine analogue on the streets — Hong Kong Medical Journal doi:10.12809/hkmj177089
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