3-HO-PCP

# Research Output: 3-HO-PCP (3-Hydroxyphencyclidine)

**PSX ID:** PSX-0048  
**Slug:** 3-ho-pcp  
**Research date:** 2026-04-26  
**Substance readiness tier:** Sparse/Emerging (< 0.3) — primary source literature is extremely limited; the majority of pharmacology data is sourced from indirect sources and analogical inference from the parent compound and class.

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## Chemical Identity

**Verified via PubChem CID 133277** [Ref 27]:

| Field | Value |
|---|---|
| Molecular formula | C₁₇H₂₅NO |
| Molecular weight | 259.4 g/mol |
| IUPAC name | 3-(1-piperidin-1-ylcyclohexyl)phenol |
| InChIKey | AMSXTZUCNOKUEN-UHFFFAOYSA-N |
| PubChem CID | 133277 |

> **Note on seed data discrepancies:** The brief's seed data was missing SMILES, InChIKey, and PubChem CID — all three are now confirmed and filled from PubChem [Ref 27]. The IUPAC name in the seed data ("3-(1-piperidin-1-ylcyclohexyl)phenol") matches PubChem exactly; no discrepancies found. SMILES string was not returned in the PubChem API response and could not be confirmed.

**CAS number:** Not returned by PubChem API; not confirmed from any retrieved source.

**Physical description:** Available from vendor/supplier literature (not peer-reviewed); described as a white-to-off-white crystalline powder. No published melting point, aqueous solubility, or stability data was located in the peer-reviewed literature.

**Stereochemistry:** 3-HO-PCP is a racemate. No literature comparing activity of individual enantiomers was located. By analogy with PCP and related arylcyclohexylamines, enantioselectivity at the NMDA receptor channel site is expected but has not been published for this compound specifically.

---

## Pharmacology

### Receptor Binding Profile

3-HO-PCP is pharmacologically distinguished from most arylcyclohexylamines by combining potent NMDA receptor antagonism with substantial μ-opioid receptor agonism. The following binding affinity values are reported in web-aggregated secondary sources (HandWiki [Ref 25], PsychonautWiki) that cite primary literature; the specific primary paper (believed to be a 1982 *Journal of Medicinal Chemistry* study) could not be directly retrieved or API-verified. All Ki values below are accordingly marked as requiring primary source verification.

| Receptor | Ki / IC50 | Notes |
|---|---|---|
| NMDA receptor (MK-801/dizocilpine site) | Ki ≈ 30 nM | Uncompetitive antagonist [Ref 25] |
| μ-opioid receptor (MOR) | Ki ≈ 39–60 nM | **Unique** among arylcyclohexylamines [Ref 25] |
| σ1 receptor | Ki ≈ 42 nM; IC50 = 19 nM | [Ref 25] |
| κ-opioid receptor (KOR) | Ki ≈ 140 nM | [Ref 25] |
| δ-opioid receptor (DOR) | Ki ≈ 2,300 nM | Low affinity [Ref 25] |

**⚠️ FLAG (Safety-Critical):** These binding affinity values are sourced from web-aggregated secondary sources. The underlying primary paper was not directly API-verified. Until the primary paper is confirmed, these values should be treated as probable but not fully verified. The trend is consistent with the autoradiographic and radioligand studies that used 3-OH-PCP as a radioligand [Ref 2][Ref 9].

**Comparison to parent compound PCP** (from same secondary aggregates [Ref 25]):
- PCP at NMDA (MK-801 site): Ki ≈ 250 nM — 3-HO-PCP is approximately 8-fold more potent
- PCP at MOR: Ki ≈ 11,000–26,000 nM — 3-HO-PCP is 282–433-fold more potent at the mu-opioid receptor
- PCP at KOR: Ki ≈ 4,100 nM; PCP at DOR: Ki ≈ 73,000 nM

The high μ-opioid affinity is the most pharmacologically distinctive feature of 3-HO-PCP and is described by multiple sources as unique among arylcyclohexylamines [Ref 25][Ref 7].

### NMDA Receptor Binding — Brain Distribution

Autoradiographic studies in rat brain using [³H]3-OH-PCP as a radioligand established brain distribution closely corresponding to [³H]TCP and [³H]MK-801 binding sites (Suzuki et al. 1995 [Ref 2]; Suzuki et al. 1996 [Ref 9]):

- **Highest density:** Hippocampal formation — stratum radiatum and oriens of CA1, dentate gyrus
- **High density:** Olfactory system, superficial layers of cortex, amygdala, thalamus
- **Low density:** Globus pallidus, cerebellum, brain stem (except superior colliculus)

The binding pattern confirmed that 3-OH-PCP binds to NMDA/PCP ion-channel complexes **in preference to sigma sites** (Suzuki et al. 1995 [Ref 2]). MK-801 strongly inhibited [³H]3-OH-PCP binding, and glutamate/glycine/polyamine site antagonists displaced it similarly to [³H]MK-801 (Suzuki et al. 1996 [Ref 9]).

### Sigma Receptor Binding (Early Work)

In rat brain membrane preparations, [³H]PCP-3-OH was used as a radioligand to characterize sigma and PCP binding sites (Itzhak & Khouri 1988 [Ref 4]; Itzhak 1988 [Ref 5]). [³H]PCP-3-OH labeled both a high-affinity component shared with (+)[³H]SKF 10047 (sigma ligand) and a lower-affinity, PCP-selective component unaffected by guanine nucleotides. These studies revealed the existence of multiple sigma and PCP binding site subtypes and established 3-HO-PCP as a prototypical radioligand for PCP receptor characterization.

### Mechanism of Action — Summary

3-HO-PCP acts as a **voltage-gated, use-dependent (uncompetitive) NMDA receptor channel blocker** at the dizocilpine/MK-801 binding site — the same mechanism as PCP, ketamine, and MK-801 [Ref 7][Ref 24]. Unlike PCP, 3-HO-PCP simultaneously acts as a significant **μ-opioid receptor agonist**, giving it a dual pharmacological profile [Ref 25][Ref 31]. The σ1 receptor activity may modulate dopaminergic transmission and other intracellular signaling [Ref 7].

This dual NMDA antagonist / mu-opioid agonist profile is predicted to:
1. Amplify CNS and respiratory depression relative to either drug class alone
2. Contribute analgesic effects beyond what NMDA antagonism alone would provide
3. Confer higher physical dependence liability than pure NMDA antagonists

### Relationship to 3-MeO-PCP

3-HO-PCP is a confirmed metabolite of 3-MeO-PCP — specifically, aromatic O-demethylation of 3-methoxyphencyclidine produces 3-hydroxyphencyclidine (Michely et al. 2017 [Ref 19]). Evidence does not support it being a human metabolite of PCP itself. This means persons using 3-MeO-PCP may be exposed to 3-HO-PCP as a biotransformation product in addition to 3-MeO-PCP directly.

### Dopamine Receptor Activity

No published data on 3-HO-PCP at dopamine receptors or transporters was located. By analogy with structurally related PCP analogs (4-MeO-PCP, 3-MeO-PCMo, PCA, 4-F-PCP), which produce reward and reinforcement via the mesolimbic dopamine pathway (Abiero et al. 2020 [Ref 10]; Abiero et al. 2021 [Ref 29]), dopaminergic involvement in 3-HO-PCP's rewarding effects is probable but unconfirmed for this specific compound.

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## Pharmacokinetics

All human pharmacokinetic data derives from a single forensic study (Davidsen et al. 2020 [Ref 3]) using samples from law enforcement seizures and forensic casework in Denmark — not controlled clinical studies.

### Plasma Protein Binding
- Unbound fraction (fu): **0.72 ± 0.09** (Davidsen et al. 2020 [Ref 3])
- Moderately plasma-bound (~28% bound); relatively high free fraction facilitates CNS distribution

### Metabolism
Four metabolites identified after in vitro incubation with pooled human hepatocytes (Davidsen et al. 2020 [Ref 3]):
1. **Piperidine-hydroxyl metabolite** — aliphatic hydroxylation of the piperidine ring
2. **N-dealkyl-COOH metabolite** — piperidine ring-opened, carboxylic acid; **dominant urinary metabolite** in deconjugated urine
3. **O-glucuronidated metabolite** — phase II conjugation of the phenolic hydroxyl
4. **O-sulfate-conjugated metabolite** — phase II conjugation; detected in vitro but NOT detected in vivo

**In vivo:** Analytical targets in blood and brain were the parent 3-HO-PCP and the O-glucuronidated metabolite; 3-HO-PCP itself had the highest relative signal intensity.

### CYP Enzyme Involvement
No specific CYP enzyme characterization was performed for 3-HO-PCP. By analogy with related compounds:
- Parent compound PCP: primarily **CYP3A4** (Laurenzana & Owens 1997 [Ref 20])
- Analogue 3-MeO-PCP: **CYP2B6** for aliphatic hydroxylations; **CYP2C19** and **CYP2D6** for O-demethylation (Michely et al. 2017 [Ref 19])

3-HO-PCP metabolism likely involves CYP2B6 and CYP3A4/5, but this is class inference only, not compound-specific data.

⚠️ **FLAG:** CYP enzyme identity for 3-HO-PCP is inferred from analogs, not directly measured. Clinically relevant CYP2D6/2C19 polymorphisms could affect exposure, but no compound-specific pharmacogenomic data exists.

### CNS Distribution
- **Brain/blood ratio (postmortem):** ~1.5 — brain concentration 1.5-fold higher than postmortem blood (Davidsen et al. 2020 [Ref 3])
- Indicates moderate-to-good CNS penetration consistent with the compound's lipophilicity

### Quantitative In Vivo Data (Forensic Samples)
| Sample | Subject status | Concentration |
|---|---|---|
| Blood | Living | 0.013 mg/kg |
| Blood | Deceased | 0.095 mg/kg |
| Urine (deconjugated) | Living | 7.8 mg/kg |
| Brain (postmortem) | Deceased | 0.16 mg/kg |

⚠️ **FLAG (Safety-Critical):** Blood concentration of 0.095 mg/kg was detected in a deceased subject, but cause of death is not established as 3-HO-PCP alone — other substances were present. This value cannot be used as a reliable lethal concentration reference.

### Half-life
No published human half-life data exists for 3-HO-PCP. The seed database value of **5.5 days** refers to tolerance half-life, not pharmacokinetic elimination half-life. No published study was found to support either value. Pharmacokinetic elimination half-life is completely unknown from clinical data.

---

## History

### Discovery and Synthesis

3-HO-PCP (3-hydroxyphencyclidine; 1-[1-(3-hydroxyphenyl)cyclohexyl]piperidine) was first synthesized in **1978** as part of systematic PCP structure-activity relationship studies, attributed to Kalir and colleagues investigating PCP derivatives in mice [Ref 25]. In the 1980s, receptor-binding studies revealed 3-HO-PCP possessed significant μ-opioid receptor agonist activity in animal preparations, distinguishing it from the parent compound PCP [Ref 5][Ref 25].

By 1988, Itzhak and colleagues were using [³H]3-OH-PCP (also designated PCP-3-OH) as a radioligand to characterize sigma and PCP receptor binding sites in rat brain membranes [Ref 4][Ref 5] — confirming its established status as a pharmacological tool compound in receptor biology research.

### Online Discussion and Research Chemical Market Emergence

In **1999**, a chemist using the pseudonym "John Q. Beagle" published observations on The Hive forum reporting 3-HO-PCP's significantly increased potency relative to PCP, specifically calling attention to its profoundly enhanced opioid receptor affinity and suggesting analgesic activity approximately one order of magnitude below morphine [Ref 25]. This constitutes the earliest publicly documented interest in 3-HO-PCP as a candidate psychoactive substance for human use.

3-HO-PCP first appeared on the **research chemical market around 2009**, with psychoactive effects described by Bluelight forum users even prior to commercial availability [Ref 25]. Law enforcement seizures followed — confirmed detections in Denmark (Davidsen et al. 2020 [Ref 3]) and UK (Dunlop et al. 2020 [Ref 1]).

As of the WHO ECDD 47th review (2024), 3-HO-PCP has been reported in **27 countries**: Austria, Australia, Bulgaria, Canada, China, Croatia, Denmark, Estonia, Finland, France, Germany, Hungary, Italy, Japan, Lithuania, Netherlands, New Zealand, Norway, Poland, Slovenia, Spain, Sweden, Switzerland, Türkiye, United Kingdom, United States, and others [Ref 14].

### Regulatory History Timeline
- **1978:** First synthesis (Kalir et al.) [Ref 25]
- **1988:** Used as pharmacological radioligand in receptor studies (Itzhak) [Ref 4][Ref 5]
- **1999:** First public human-use discussion ("John Q. Beagle," The Hive) [Ref 25]
- **2009:** Emergence on research chemical market [Ref 25]
- **2018 (June 28):** Banned in Sweden [Ref 25]
- **2024 (August):** US Federal Register published request for public comment on WHO scheduling review [Ref 15]
- **2024 (October 14–18):** WHO ECDD 47th Expert Committee reviewed 3-OH-PCP for international scheduling [Ref 14]

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## Subjective Effects

No controlled human studies or clinical self-report studies exist for 3-HO-PCP. Published descriptions derive exclusively from:
1. A single analytically confirmed case report of severe toxicity (Dunlop et al. 2020 [Ref 1]) — describes adverse/toxic manifestations, not a typical subjective profile
2. Extrapolation from the PCP pharmacological class [Ref 6][Ref 7]
3. Community self-reports on harm reduction forums (Bluelight, PsychonautWiki) — not peer-reviewed [Ref 25]

By pharmacological class (NMDA antagonist + opioid agonist), the expected subjective profile includes dissociative and analgesic effects, with the opioid component anticipated to add a more pronounced euphoric/sedative and body-warmth character compared to pure NMDA antagonists like ketamine or 3-MeO-PCP. The dual receptor profile may produce a qualitatively distinct experience compared to other arylcyclohexylamines.

### Duration Data (from seed database — community consensus origin)
| Phase | Duration (oral) |
|---|---|
| Come-up | 60–90 minutes |
| Total | 4–6 hours |

These values are consistent with the oral route's slower absorption and the compound's lipophilicity. No primary source confirmation was found.

### Dose Data (from seed database — community consensus origin)
| Level | Dose (oral) |
|---|---|
| Threshold | 1 mg |
| Light | 2–4 mg |
| Common | 4–6 mg |
| Strong | 6–8 mg |
| Heavy | 8+ mg |

⚠️ **FLAG (Safety-Critical):** These dose ranges are derived from community consensus (PsychonautWiki) and have not been validated by any controlled study or clinical series. Given 3-HO-PCP's substantially higher potency than PCP at both NMDA (8-fold) and opioid receptors (282–433-fold at MOR) [Ref 25], and the complete absence of any established therapeutic index, these values carry substantial uncertainty. Dose ranges should be flagged for editorial review before publication.

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## Safety & Toxicity

### Lethal Dose and LD50
**No LD50 data available for any species.** Toxic dosage is explicitly unknown. The WHO ECDD 47th review noted no preclinical toxicology studies were available for 3-hydroxyphencyclidine [Ref 14].

### Case Reports of Adverse Events

**Dunlop et al. 2020 [Ref 1]** — Analytically confirmed case of severe toxicity:
- Substances: 3-HO-PCP + N-ethylhexedrone (synthetic cathinone stimulant); polydrug exposure
- Setting: UK clinical presentation
- Outcome: Severe toxicity requiring medical management

**Davidsen et al. 2020 [Ref 3]** — Postmortem forensic context:
- One deceased individual with blood concentration 0.095 mg/kg 3-HO-PCP
- Multiple other substances present; causation not established

**WHO ECDD 47th Review [Ref 14]** (public version summary):
> "Isolated cases of morbidity or mortality associated with exposure to analytically confirmed 3-hydroxyphencyclidine have been reported in the literature. As other substances were detected in all cases, the degree to which the substance contributed to clinical effects or mortality cannot be determined conclusively. In none of the fatal and nonfatal cases was 3-hydroxyphencyclidine the only substance detected; the other identified substances included benzodiazepines, opioids and stimulants."

### Organ Toxicity
- No organ-specific toxicity studies published for 3-HO-PCP
- **Rhabdomyolysis risk** documented for PCP analog class (3-methyl-PCP case: Deutsch et al. 2026 [Ref 12]); acute kidney injury secondary to rhabdomyolysis is a plausible class risk
- No urinary tract / bladder toxicity analogous to ketamine cystopathy has been specifically documented for 3-HO-PCP, but chronic use data is absent

### Respiratory Depression Risk — Unique to 3-HO-PCP

The combination of NMDA antagonism with intrinsic μ-opioid agonism (Ki ≈ 39–60 nM) creates a **compound risk for respiratory depression** beyond what either pharmacological mechanism alone produces [Ref 25][Ref 31]. This is a critical and **substance-specific** safety consideration that distinguishes 3-HO-PCP from most other PCP analogs (which lack meaningful opioid activity). All known serious cases involved co-ingestion of CNS depressants [Ref 14].

### Psychosis Risk
By NMDA antagonism, 3-HO-PCP carries psychotomimetic risk analogous to PCP and ketamine — capable of inducing positive symptoms (hallucinations, paranoia), negative symptoms (emotional withdrawal, motor retardation), and formal thought disorder (Javitt & Zukin 1991 [Ref 18]; Coyle 2012 [Ref 24]). Heavy or chronic use carries risk of persistent psychosis.

### Detection
Standard urine immunoassay PCP screens detect only approximately 20% of PCP structural analogs (Regester et al. 2015 [Ref 21]), making standard drug testing likely to miss 3-HO-PCP in clinical and forensic contexts. Confirmatory LC-HRMS methods have been developed and validated (Davidsen et al. 2020 [Ref 3]).

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## Harm Reduction

### Key Substance-Specific Risks to Communicate
1. **Respiratory depression risk is elevated above typical dissociatives** due to μ-opioid agonism — this is a substance-specific property not shared by ketamine, 3-MeO-PCP, or most arylcyclohexylamines, and will not be anticipated by users with experience of those compounds
2. **Polydrug combinations dramatically increase risk:** All documented serious adverse events involved other substances (opioids, benzodiazepines, stimulants) [Ref 14][Ref 1]
3. **No established safe dose:** Toxic dose is unknown; the dose-effect curve in humans is uncharacterized
4. **Standard drug tests will not detect 3-HO-PCP:** Emergency clinicians need to be informed to use LC-MS/MS or similar confirmation methods [Ref 21][Ref 3]

### Analytical Testing Recommendations
- Immunoassay PCP screens: likely to produce a negative result (only ~20% cross-reactivity for PCP analogs) [Ref 21]
- Confirmatory identification: LC-HRMS/MS required [Ref 3]
- Reagent test response: Not confirmed in peer-reviewed literature; phenolic structure may produce Marquis color change but unverified

### Emergency Response
No specific antidote or established treatment protocol exists. Management is supportive. Importantly:
- Given intrinsic μ-opioid agonism, **naloxone** may partially reverse respiratory depression — this pharmacological rationale is not standard for PCP analog overdose but is supported by the compound's receptor profile [Ref 25][Ref 31]
- Benzodiazepines are first-line for agitation and psychomotor symptoms, consistent with standard NPS treatment guidelines (Ordak et al. 2021 [Ref 23])
- Monitor closely for respiratory depression, particularly in polydrug contexts

⚠️ **FLAG:** Naloxone efficacy in 3-HO-PCP overdose is pharmacologically indicated but has not been clinically validated. This is an important and unresolved harm reduction knowledge gap.

---

## Tolerance & Dependence

### Seed Database Values (Not Verified Against Primary Sources)
| Parameter | Seed value | Verification status |
|---|---|---|
| Tolerance buildup | With prolonged/repeated use | Unverified; plausible by class |
| Tolerance half-life | 5.5 days | **No source found** |
| Full reset | ~1.5 weeks | **No source found** |
| Cross-tolerances | Dissociative drug class | Plausible by class |

⚠️ **FLAG:** No published primary source was found for these specific tolerance kinetics. The 5.5-day half-life value appears to be editorial estimation. Both the tolerance half-life and full-reset values should remain provisional pending editorial review.

### Pharmacological Basis for Dependence

3-HO-PCP's dual pharmacological profile creates a higher theoretical dependence liability than either mechanism alone:

- **Opioid-type physical dependence:** μ-opioid agonism (Ki ≈ 39–60 nM) predicts physical dependence formation with repeated use by the same mechanism as opioid drugs [Ref 25]. No published animal studies specifically confirm this for 3-HO-PCP, but the mechanism is well-established for the MOR agonist class
- **Dissociative-type psychological dependence:** Abuse potential via mesolimbic dopamine pathway is documented for PCP analogs (Abiero et al. 2020 [Ref 10]; Abiero et al. 2021 [Ref 29])

The seed database classification of "moderate" physical and psychological dependence and "moderately addictive with high potential for adverse side effects such as psychosis" is pharmacologically plausible given the dual receptor profile but is not confirmed by any substance-specific published study.

---

## Interactions

### CNS Depressants — HIGH RISK
- **Opioids:** Additive and potentially synergistic respiratory depression; 3-HO-PCP's intrinsic μ-opioid activity makes this combination particularly dangerous and synergistic rather than merely additive [Ref 25][Ref 14]
- **Benzodiazepines:** Additive CNS depression, sedation, respiratory depression; all documented serious 3-HO-PCP cases involved co-present benzodiazepines [Ref 14]
- **Alcohol:** Additive CNS depression; documented in PCP analog cases [Ref 26]

### Stimulants — ELEVATED RISK
- Documented in Dunlop 2020 [Ref 1]: 3-HO-PCP + N-ethylhexedrone (cathinone stimulant) produced severe toxicity
- Cardiovascular stress: stimulant + dissociative combinations associated with cardiac and hypertensive events

### CYP Drug Interactions (Class Inference)
By analogy with 3-MeO-PCP (CYP2B6/2C19/2D6) and PCP (CYP3A4) [Ref 19][Ref 20]:
- **CYP2B6 inhibitors** (e.g., ticlopidine, clopidogrel): may increase 3-HO-PCP plasma exposure
- **CYP3A4 inhibitors** (e.g., ketoconazole, certain antiretrovirals, grapefruit): may increase exposure
- **CYP2D6 inhibitors** (e.g., paroxetine, fluoxetine): may alter metabolite profile and increase parent drug exposure
- These are class inferences, not compound-specific data; no direct interaction studies exist

### Serotonin Syndrome Risk
No evidence of serotonergic activity for 3-HO-PCP was located. Risk of serotonin syndrome with serotonergic agents is not specifically indicated by known pharmacology, though a complete receptor profile has not been published.

---

## Legal Status

| Jurisdiction | Status | Notes |
|---|---|---|
| **United States** | Unscheduled (federal) | Prosecutable under Federal Analogue Act (21 U.S.C. §813) when intended for human consumption; qualifies as PCP positional isomer [Ref 15][Ref 25] |
| **United Kingdom** | Class B | Misuse of Drugs Act 1971; covered by arylcyclohexylamine generic clause [Ref 25] |
| **Canada** | Schedule I | Controlled Drugs and Substances Act [Ref 25] |
| **Germany** | NpSG restricted | Industrial and scientific use only under New Psychoactive Substances Act [Ref 25] |
| **Sweden** | Banned | Prohibited June 28, 2018 [Ref 25] |
| **Switzerland** | Banned | [Ref 25] |
| **International** | Not under international control (as of early 2024) | WHO ECDD 47th meeting reviewed for possible scheduling under the 1971 Convention, October 2024 [Ref 14][Ref 15] |

The US Federal Register notice of August 2024 [Ref 15] solicited public comment on WHO ECDD assessment of 3-hydroxy-phencyclidine, indicating international scheduling was under active consideration as of that date.

---

## Clinical Trials

**No clinical trials registered.** ClinicalTrials.gov search for "3-HO-PCP" and "hydroxyphencyclidine" returned zero results. This is consistent with 3-HO-PCP having no known medical application or established therapeutic interest.

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## Community Feedback Analysis

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

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## Gaps & Flags

### 🔴 Safety-Critical Gaps

**1. Toxic and lethal dose unknown.**  
No LD50 data exists for any species. The threshold for dangerous human exposure cannot be established from published evidence. **[Requires prominent editorial warning in article.]**

**2. Binding affinity Ki values sourced from web aggregates only.**  
The Ki values (NMDA Ki=30nM, MOR Ki=39–60nM, σ1 Ki=42nM, KOR Ki=140nM, DOR Ki=2300nM) appear in multiple secondary aggregates (HandWiki [Ref 25], PsychonautWiki) citing a *J. Med. Chem.* 1982 primary paper that could not be directly retrieved or API-verified. Values are internally consistent and cross-corroborated but are not api_verified. The generation agent should treat these as probable values requiring primary source citation before publication.

**3. Dose ranges not verified against primary sources.**  
Seed database dose ranges match PsychonautWiki community consensus. Given 3-HO-PCP's substantially higher potency than PCP (8-fold at NMDA; 282–433-fold at MOR), under-dosing assumptions drawn from PCP analog experience could produce dangerous outcomes. Dose data requires editorial review before article publication.

**4. Blood concentration 0.095 mg/kg (deceased subject) cannot be treated as lethal reference.**  
Cause of death not established as 3-HO-PCP alone; multiple co-present substances.

### 🟡 Moderate Data Gaps

**5. No controlled human pharmacokinetic study.**  
Plasma protein binding, metabolite profile, and in vivo concentrations derive from forensic case samples only [Ref 3]. No Tmax, bioavailability, volume of distribution, or elimination half-life data.

**6. Tolerance half-life (5.5 days) in seed database has no identifiable primary source.**  
Should be treated as provisional editorial estimation.

**7. CYP enzyme involvement not directly characterized for 3-HO-PCP.**  
Estimates by class analogy from PCP (CYP3A4) and 3-MeO-PCP (CYP2B6, CYP2C19, CYP2D6) are appropriate but must be labeled as class inference in article prose.

**8. Stereochemistry / enantiomeric activity not published.**  
3-HO-PCP is sold as a racemate; differential receptor activity of enantiomers is unstudied.

**9. Original synthesis paper (Kalir et al. 1978) not directly retrieved or API-verified.**  
Referenced in secondary sources as a *ChemInform Abstract* but exact journal, volume, and page not confirmed. This is cited as foundational history; the specific citation details require verification.

**10. WHO ECDD 47th recommendation not yet accessible.**  
The October 2024 meeting reviewed 3-HO-PCP; the final scheduling outcome and committee recommendation were not accessible in the research conducted. Final outcome may have resulted in a recommendation for international scheduling under the 1971 Convention — should be verified before article publication.

**11. Naloxone efficacy in 3-HO-PCP overdose not clinically studied.**  
Pharmacologically indicated based on MOR Ki data, but no clinical evidence exists. Critical harm reduction knowledge gap.

**12. "Dopamine receptor ligand" in seed pharmacological class — no primary evidence found.**  
No published binding data for 3-HO-PCP at dopamine receptors or transporters. This classification appears to be class inference from PCP analogs broadly. Generation agent should use cautious language and label as class inference.

**13. Contraindications not documented in literature.**  
No published study addresses contraindications specifically. By class pharmacology, probable contraindications include: history of psychosis or schizophrenia (NMDA antagonism), respiratory insufficiency (opioid agonism), hepatic impairment (CYP-dependent metabolism), concurrent use of opioids or other CNS depressants, and history of opioid dependence. These should be stated as class-inferred contraindications, not substance-confirmed.

**14. No peer-reviewed human self-report or observational data on typical subjective effects.**  
All published human data is from emergency toxicology cases reporting adverse outcomes only. Duration, come-up, and effect quality data are community-consensus only [Ref 25].