O-PCE
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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.
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ketamine, deschloroketamine, methoxetamine +3 moreketamine, deschloroketamine, methoxetamine, PCP, DXM, nitrous oxide show less
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.
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
No 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.
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
- [2]
- [3]
- [4]
- [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
- [6]