2-Fluorodeschloroketamine

# Research Output: 2-Fluorodeschloroketamine (2-FDCK)

## Chemical Identity

**Verified via PubChem CID 13771618** [Ref 5 — Nadarajan et al. 2024, PubChem database]:

| Property | Value | Source |
|---|---|---|
| IUPAC Name | 2-(2-fluorophenyl)-2-(methylamino)cyclohexan-1-one | PubChem CID 13771618 |
| Molecular Formula | C₁₃H₁₆FNO | PubChem, UNODC |
| Molecular Weight | 221.27 g/mol | PubChem |
| InChIKey | PHFAGYYTDLITTB-UHFFFAOYSA-N | PubChem, UNODC |
| CAS Number (free base) | 111982-50-4 | UNODC, ChemicalBook |
| CAS Number (HCl salt) | 111982-49-1 | Cayman Chemical |
| PubChem CID | 13771618 | Confirmed via PubChem API |

**Discrepancies with seed data:**
- Seed data left SMILES, molecular formula, molecular weight, InChIKey, and PubChem CID blank. All are now confirmed above.
- The IUPAC name in the seed data ("2-(2-fluorophenyl)-2-(methylamino)cyclohexan-1-one") is correct and matches PubChem.
- Two CAS numbers exist: 111982-50-4 for the free base form and 111982-49-1 for the hydrochloride salt. This dual-CAS situation is common for NPS compounds and both resolve to the same substance.

**Alternative names confirmed in literature:** 2-FDCK, 2F-DCK, fluoroketamine, 2'-Fl-2-Oxo-PCM (Wallach & Brandt 2018 [Ref 6]).

---

## Pharmacology

### Mechanism of Action

**⚠️ FLAG: No published receptor binding affinity data (Ki/EC50) have been reported for 2-FDCK at any target in the primary literature.** All pharmacological characterization is by structural analogy to ketamine and the arylcyclohexylamine class (Wallach & Brandt 2018 [Ref 6]; WHO ECDD 2023 [Ref 17]).

The WHO 46th ECDD Critical Review (2023) [Ref 17] states that "the mechanism remains uncertain" and that effects mirror those of NMDA receptor antagonists such as phencyclidine. All three receptor targets listed in the seed data are inferred:

**1. NMDA Receptor Antagonism (primary mechanism — inferred)**
2-FDCK is an arylcyclohexylamine with the core ketamine scaffold (2-phenyl-2-aminocyclohexan-1-one backbone). Ketamine acts as an uncompetitive (open-channel) NMDA receptor antagonist, binding within the channel pore at the phencyclidine site. By close structural homology — specifically the replacement of ketamine's 2-chloro substituent with 2-fluoro — the same mechanism is strongly predicted. Pharmacological verification via drug discrimination testing showed 2-FDCK dose-dependently substituted for ketamine with a comparable ED₅₀, which is consistent with a shared NMDA-mediated mechanism (Li et al. 2022 [Ref 12]).

**2. Dopamine Reuptake Inhibition (inferred)**
Arylcyclohexylamine class compounds, including ketamine and methoxetamine, act as dopamine reuptake inhibitors. This is considered a shared class property contributing to their stimulant and rewarding qualities (Coppola & Mondola 2012 [Ref 7]; Wallach & Brandt 2018 [Ref 6]).

**3. Sigma-1 Receptor Agonism (inferred)**
Ketamine binds sigma-1 and sigma-2 receptors at µM affinities (Robson et al. 2012 [Ref 15]). This property is shared across arylcyclohexylamines. No sigma binding data for 2-FDCK specifically are published.

**Preclinical abuse liability:**
Preclinical rodent studies provide the strongest direct pharmacological data for 2-FDCK:
- Li et al. (2022) [Ref 12] found 2-FDCK induced conditioned place preference (CPP) at a minimum dose of 3 mg/kg (mice), comparable to ketamine at the same dose. Locomotor sensitization developed with repeated 30 mg/kg dosing. Self-administration at 0.5 mg/kg/infusion (IV, same dose as ketamine). Drug discrimination: dose-dependent substitution for ketamine, comparable ED₅₀.
- Du et al. (2022) [Ref 11] compared reinforcing efficacy via behavioral economics demand curves and found the elasticity parameter α and essential value were similar between 2F-DCK and ketamine in IV self-administration (0.5 mg/kg/infusion, FR1, 4h/day). Both compounds reinstated drug-seeking via cue and drug-prime. BDNF and p-CREB downregulated in nucleus accumbens; Akt/mTOR/GSK-3β signaling upregulated in reinstated rats.

### Pharmacokinetics

**⚠️ FLAG: No controlled human pharmacokinetic studies have been published for 2-FDCK.** Available data are from forensic case samples and toxicokinetic modeling.

**Blood concentrations (forensic):**
- Davidsen et al. (2020) [Ref 13] reported blood 2-FDCK concentrations of 0.005–0.48 mg/kg in driving under the influence of drugs (DUID) cases in Denmark. Segmental hair analysis yielded 0.007–0.034 ng/mg.
- Riess et al. (2024) [Ref 3] reported peripheral blood concentrations in two fatal cases: 457 µg/L (self-mutilation case), 758 µg/L (homicide victim), and 5,885 µg/L (suspected overdose death).

**Hepatic clearance:**
Davidsen et al. (2020) [Ref 13] performed in vitro–in vivo extrapolation (IVIVE) comparing ketamine analogues: Hepatic clearance ranking was **Ketamine > Norketamine = 2-FDCK > Methoxetamine > Deschloroketamine**. A negative correlation was observed between ortho-halogen molecular weight and IVIVE clearance — fluorine's lower molecular weight compared to chlorine predicts moderately higher hepatic clearance for 2-FDCK versus DCK but lower than ketamine.

**Protein binding:**
Unbound fraction (fu) for the series was 0.54–0.84 (Davidsen et al. 2020 [Ref 13]); specific fu for 2-FDCK is within this range but exact value not isolated in abstract.

**Renal excretion:**
Shao et al. (2021) [Ref 16] predicted a renal clearance excretion factor of 3.7 for 2-FDCK using a quantitative structure–pharmacokinetic relationship model.

**Analog inference — oral bioavailability:**
By analogy to ketamine, oral bioavailability is expected to be substantially reduced by hepatic first-pass metabolism. Ketamine has oral bioavailability of ~17–29% due to CYP-mediated first-pass (Nguyen et al. 2022 [Ref 26]). The seed data's oral dose ranges (threshold 5 mg, common 25–70 mg) appear consistent with a less potent oral route versus insufflation (threshold 5 mg, common 45–100 mg), which is consistent with analogy.

**CYP enzymes (inferred):**
By analogy to ketamine, N-demethylation to nor-2F-DCK is predicted to involve CYP3A4, CYP2B6, and CYP2C9 as the primary enzymes (Nguyen et al. 2022 [Ref 26]). This inference is supported by the prominence of nor-2F-DCK as the primary detected metabolite across all published studies [Refs 2, 8, 10, 23].

### Metabolites (Human — Confirmed)

Joseph et al. (2023) [Ref 2] identified **26 putative metabolites** in pooled human liver microsomes (pHLMs), urine, and hair from a chronic user (15 novel). Metabolic pathways:
1. **N-demethylation** → nor-2F-DCK (confirmed primary metabolite and recommended forensic target)
2. **Carbonyl reduction (hydrogenation)** → dihydro-2F-DCK
3. **Combined N-demethylation + reduction** → dihydro-nor-2F-DCK
4. **Hydroxylation** → multiple hydroxy derivatives
5. **Glucuronidation** → Phase II conjugates (minor; unstable in wastewater)

**Deschloroketamine (DCK) as a 2-FDCK metabolite:** Joseph et al. (2023) [Ref 2] was the first to report DCK in pHLMs from 2-FDCK incubation and confirmed its presence in hair of a chronic 2-FDCK user (hair concentrations: 885/1,500/1,850 pg/mg across three 3-cm segments). This finding has forensic implications as DCK-positive tests may indicate 2-FDCK use rather than direct DCK consumption.

Luo et al. (2023) [Ref 4] characterized the full set of oxidative metabolites via LC-IT-TOF-MS in human urine, identifying 17 compounds in 4 oxidative groups. The two enantiomers of dihydro-2-FDCK were characterized, with stereoselectivity of hydrogenation enzymes clarified.

Gicquel et al. (2022) [Ref 10] using molecular networking across HLM and HepaRG cell models found 13 in vitro metabolites and 7 additional metabolites in post-mortem samples. Proposed nor-2F-DCK (208.1137 m/z) and the hydrogenated metabolite (224.1443 m/z) as primary HRMS library targets.

### Stereochemistry

2-FDCK is a chiral molecule and is marketed as a racemate (R,S mixture). No published data characterize the relative potency or NMDA binding affinity of the individual R- and S-enantiomers of 2-FDCK specifically. By analogy to ketamine (where S-ketamine has approximately 4× greater NMDA affinity than R-ketamine), the S-enantiomer may be more potent, but this is unconfirmed for 2-FDCK [Refs 6, 17]. **⚠️ FLAG: Enantiomeric pharmacology is a significant gap — flagged for future research.**

---

## History

**Original synthesis (1987):**
Wang S-y and Li C-x first synthesized 2-FDCK, published as "Synthesis of anesthetic compound 2-(o-fluorophenyl)-2-methylamino-cyclohexanone hydrochloride (F-ketamine)" in Beijing Daxue Xuebao (Journal of Peking University), 1987 [Ref 28]. This predates the compound's NPS market emergence by approximately 30 years.

**Modern synthesis characterization (2014):**
Moghimi et al. (Synthetic Communications, 2014) [Ref 27] published a detailed synthesis of 2-FDCK via a five-step reaction beginning with 2-fluorobenzonitrile and a Grignard reagent, with the final step being a thermal ring-expansion rearrangement from a cyclopentanol intermediate to the cyclohexylketone product. This synthesis became the primary reference for clandestine producers.

**Chemical precursor identified:**
Luo et al. (2022) [Ref 23] identified 1-[(2'-fluorophenyl)(methylimino)methyl]cyclopentan-1-ol (2-fluorodeschlorohydroxylimine) as the suspected clandestine synthesis precursor of 2-FDCK, by analogy to the role of hydroxylimine in ketamine synthesis. Full decomposition pathways were characterized.

**Market emergence:**
- **2015:** First online forum discussions of 2-FDCK as a compound (web sources).
- **2016:** First formal EMCDDA notification alongside 65 other new substances. First documented detection by government authorities in Spain (Wallach & Brandt 2018 [Ref 6]; WHO ECDD 2023 [Ref 17]).
- **2017:** Became more widely available on online research chemical markets, marketed as a "legal replacement for ketamine."
- **2018:** Detected in wastewater in Guangzhou, China — earliest confirmed presence in Chinese environmental samples (Shao et al. 2021 [Ref 16]).
- **2019:** First clinical case series documented (20 cases, Hong Kong, Jan–Jul 2019) (Tang et al. 2020 [Ref 8]).
- **2021:** First US case report, described as a "relatively new agent not yet reported in the United States" (Domanski et al. 2022 [Ref 1]).
- **2023–2024:** WHO 46th ECDD recommended Schedule II (October 2023 [Ref 17]); CND 67th session voted Schedule II under the Convention on Psychotropic Substances 1971 (March 2024 [Ref 19]).
- **2026:** DEA announced temporary Schedule I placement (effective February 19, 2026) [Ref 18].

**Geographic spread:**
2-FDCK has been detected in wastewater, drug seizures, and clinical/forensic cases in Australia, Austria, Canada, China, Denmark, Finland, France, Hong Kong, Italy, the Netherlands, Spain, the United Kingdom, and the United States (WHO ECDD 2023 [Ref 17]; Love & Jones 2023 [Ref 25]; Cheng et al. 2024 [Ref 14]).

---

## Subjective Effects

No controlled human dosing studies have been conducted. Effect descriptions derive from:
1. Clinical case series (observational, emergent presentations)
2. User self-reports from online communities

**Clinically documented effects** (from Tang et al. 2020 [Ref 8]; Domanski et al. 2022 [Ref 1]; WHO ECDD 2023 [Ref 17]):
- *Neurological:* impaired consciousness, agitation, abnormal behavior, nystagmus, hallucinations, dissociation/confusion
- *Cardiovascular:* hypertension, tachycardia
- *Severe:* loss of consciousness (5/20 cases in Tang et al.); convulsions (included in the 5/20)

**WHO ECDD clinical effects summary** [Ref 17]: "dissociation, confusion, agitation, combativeness, nystagmus, hallucinations, impaired/loss of consciousness, tachycardia, hypertension."

**User-reported effects** (consistent with the effects taxonomy in the brief): These include visual and perceptual changes, cognitive disconnection, depersonalization/derealization, analgesia, and time distortion — consistent with the dissociative class profile and with ketamine's established phenomenology. **⚠️ FLAG: All effect taxonomy data in the seed data are user-report–based, not from controlled studies.**

**Qualitative comparison to ketamine:**
Drug discrimination studies confirm 2-FDCK produces ketamine-like interoceptive effects — rats trained to discriminate ketamine generalized dose-dependently to 2-FDCK with comparable ED₅₀ (Li et al. 2022 [Ref 12]).

**Duration — user-report basis:**
The seed data duration values (insufflated: onset 1–3 min, total 1.5–3h; oral: onset 15–50 min, total 2.5–5h) are consistent with the arylcyclohexylamine class and with Wallach & Brandt's (2018) [Ref 6] characterization of 2-FDCK's duration relative to ketamine. No controlled study has confirmed these values. They are reasonable by structural analogy but carry user-report confidence only.

---

## Safety & Toxicity

### Established Toxicity Data

**LD₅₀:**
No LD₅₀ data have been published for 2-FDCK in any species. **⚠️ FLAG: Seed data note "exact toxic dosage is unknown" — confirmed. No LD₅₀ data available.**

**Therapeutic index:**
Unknown. Not determinable without LD₅₀ or toxic dose data.

**Fatal blood concentrations:**
Riess et al. (2024) [Ref 3] reported peripheral blood concentrations in two confirmed deaths and one self-mutilation case:
- Case 1 (self-mutilation): 457 µg/L peripheral blood
- Case 2 (found dead, stabbed): 758 µg/L peripheral blood  
- Case 3 (suspected overdose, advanced putrefaction): 5,885 µg/L peripheral blood

In Case 3, DCK was also found in biological fluids and a DCK powder seized at home — suggesting polysubstance use. In Case 2, DCK was found in biological fluids without confirmed co-use of DCK, suggesting possible 2-FDCK→DCK metabolism contributing to the forensic picture.

The Gicquel et al. (2021) [Ref 9] case involved a 42-year-old man found dead with both 2F-DCK and 3-MeO-PCE detected; death was attributed primarily to respiratory depression in a polydrug context.

**Clinical case outcomes:**
In the largest clinical series (Tang et al. 2020 [Ref 8], n=20), all patients recovered uneventfully with supportive management, suggesting 2-FDCK in isolation at typical recreational doses is survivable with appropriate medical support. However, 5 of 20 cases involved loss of consciousness or convulsions, indicating a narrow margin between recreational and medically serious doses.

### Organ Toxicity (Inferential)

**Urinary/bladder toxicity risk (inferred):**
Chronic ketamine abuse is well-established to cause severe lower urinary tract symptoms, ketamine cystitis, and potentially irreversible bladder contracture and hydronephrosis (Chu et al. 2008 [Ref 30 — FLAG: not yet in registry]; Tran et al. 2014 [Ref 31 — FLAG]). The structural relationship of 2-FDCK to ketamine raises concern that chronic 2-FDCK use may carry similar uroepithelial toxicity risk. **⚠️ FLAG: No published data on 2-FDCK–specific bladder/urinary tract toxicity. Ketamine bladder toxicity literature (e.g., Chu et al. 2008) is by structural analogy only.**

**Cardiovascular:**
Documented in clinical cases: tachycardia and hypertension are the primary acute cardiovascular effects (Tang et al. 2020 [Ref 8]; WHO ECDD 2023 [Ref 17]).

### Psychological Risks

**Self-mutilation:**
One confirmed case of self-mutilation associated with 2-FDCK intoxication (Riess et al. 2024 [Ref 3]).

**Psychosis/dissociation:**
Agitation, abnormal behavior, and hallucinations documented in clinical presentations (Tang et al. 2020 [Ref 8]; WHO ECDD 2023 [Ref 17]).

**Contamination risk:**
Seized 2-FDCK crystals analyzed by Joseph et al. (2023) [Ref 2] contained 67% and 96% 2-FDCK with traces of DCK (0.4% and 0.6%), likely from container cross-contamination. This indicates some purity variability in street samples. 2-FDCK was also identified as an adulterant in supposed 3-MMC samples in a French drug-checking study (Willeman et al. 2023 [Ref — see wastewater/festival data]).

---

## Harm Reduction

### Established Guidance

No 2-FDCK-specific clinical harm reduction guidelines have been published. The following is derived from the documented case literature:

1. **Supportive care is effective for acute intoxication:** All 20 cases in the Tang et al. (2020) [Ref 8] series recovered with supportive management. Emergency management is analogous to ketamine intoxication.

2. **Respiratory monitoring is critical:** Fatal cases involve respiratory depression in polydrug contexts (Gicquel et al. 2021 [Ref 9]; Riess et al. 2024 [Ref 3]). CNS depressant co-use is the primary modifiable fatality risk.

3. **Drug checking is advised:** 2-FDCK has been found as an adulterant in other substances (Willeman et al. 2023 [Ref 4 in OpenAlex results]; Joseph et al. 2023 [Ref 2]). Reagent testing and fentanyl strips should be used.

4. **Polydrug context accounts for most severe outcomes:** In Tang et al. 2020 [Ref 8], 19/20 cases involved at least one other ketamine-type drug alongside 2-FDCK. Multiple dissociatives combined substantially elevate risk.

### Contraindications (Analogy-Based)

No 2-FDCK-specific contraindications have been published. By analogy to ketamine and the class:
- Cardiovascular disease, history of hypertension (tachycardia/BP elevation documented)
- History of psychosis
- Urological conditions  
- Respiratory compromise
- Combination with CNS depressants (especially see Interactions section)

### Analytical Detection

**Immunoassay:** Standard ketamine immunoassay screens may not detect 2-FDCK or its metabolites. Nor-2-FDCK may cross-react with some commercial ketamine assays, but this has not been systematically characterized (Domanski et al. 2022 [Ref 1]).

**Confirmatory methods:** LC-MS/MS and LC-HRMS using nor-2F-DCK as the primary target analyte (confirmed by Joseph et al. 2023 [Ref 2] and Gicquel et al. 2022 [Ref 10]).

---

## Tolerance & Dependence

### Tolerance

**Seed data values** (buildup: prolonged/repeated use; half-life: 5 days; full reset: 1.5 weeks; cross-tolerance: dissociatives) are community-reported. **⚠️ FLAG: No published pharmacological studies confirm the tolerance half-life of 5 days or the 1.5-week reset timeline specifically for 2-FDCK. These values are plausible by class analogy but lack primary source confirmation.**

Cross-tolerance with other NMDA antagonists (ketamine, DCK, methoxetamine) is expected by shared mechanism and supported by drug discrimination data showing full generalization between 2-FDCK and ketamine (Li et al. 2022 [Ref 12]).

### Dependence

**Published evidence:**
Clinical dependence with regular use has been documented. Joseph et al. (2023) [Ref 2] reported extensive metabolism data from a self-described "addicted patient" — a confirmed chronic daily user whose hair segments (representing approximately 9 months of use) showed high 2-FDCK concentrations, including DCK as a metabolite from chronic use.

**Preclinical evidence:**
Du et al. (2022) [Ref 11] demonstrated:
- Significant drug-seeking reinstatement by both conditioned cues and drug priming (comparable to ketamine)
- Reduced BDNF and p-CREB in nucleus accumbens in extinguished and reinstated rats
- Upregulation of Akt/mTOR/GSK-3β pathway

Li et al. (2022) [Ref 12]: confirmed CPP, locomotor sensitization, self-administration, and drug discrimination all at doses comparable to ketamine — supporting comparable dependence liability.

**WHO/DEA assessment:**
WHO 46th ECDD [Ref 17]: "Clinical admissions for dependence have been reported across multiple countries." DEA (2026) [Ref 18]: Found sufficient abuse potential for Schedule I placement.

**Withdrawal:**
No published characterization of 2-FDCK-specific withdrawal. By analogy to ketamine (Blachut et al. 2009 [Ref 29]): primarily psychological symptoms (anxiety, sleep disturbance), without prominent somatic withdrawal syndrome.

---

## Interactions

**⚠️ FLAG: All interaction severity data in the seed data (Alcohol: lethal; GHB: lethal; GBL: lethal; Tramadol: lethal) are class-based analogical inferences. No 2-FDCK-specific drug interaction studies exist in the published literature.**

### Published Data (Indirect)

**Alcohol / CNS depressants (Lethal — analogy-supported):**
The fatal cases involving 2-FDCK (Riess et al. 2024 [Ref 3]; Gicquel et al. 2021 [Ref 9]) involved polydrug contexts. Gicquel et al. [Ref 9] attributed death to respiratory depression from polydrug use (2-FDCK + 3-MeO-PCE). Respiratory depression is the expected combined effect of CNS depressants. Alcohol, GHB, and GBL are all CNS depressants that would compound the respiratory suppressive and sedative effects of a dissociative.

**GHB / GBL (Lethal — analogy-supported):**
By class mechanism, GABA-B agonism (GHB/GBL) combined with NMDA antagonism produces additive CNS depression. No 2-FDCK + GHB study exists. The "lethal" designation in the seed data is consistent with established GHB + CNS depressant interaction patterns but is not verified specifically for 2-FDCK.

**Tramadol (Lethal — analogy-supported):**
Tramadol is an atypical opioid with serotonin-norepinephrine reuptake inhibitory properties and weak opioid agonism. Potential for seizures when combined with drugs that lower seizure threshold (NMDA antagonism may be protective for some seizures, but tramadol's proconvulsant metabolite m-ODT adds complexity). Additionally, combined respiratory depression. No 2-FDCK + tramadol study exists. **⚠️ FLAG: The "lethal" severity for tramadol specifically needs editorial review. The pharmacological basis is more complex than for pure CNS depressants.**

---

## Legal Status

### International
- **UN Convention on Psychotropic Substances (1971):** Schedule II, effective 2024. WHO 46th ECDD recommended Schedule II in October 2023 [Ref 17]; CND 67th session voted to implement in March 2024 [Ref 19]. UNODC entry confirms "71/II" status [confirmed via UNODC LSS database].

### United States
- **DEA Schedule I** (temporary): Announced January 20, 2026, effective February 19, 2026 (Federal Register 2026-00954) [Ref 18]. Previously unscheduled at federal level.

### United Kingdom
- Controlled under the **Psychoactive Substances Act 2016**, which prohibits all psychoactive substances not otherwise exempted. 2-FDCK has no exemption. **⚠️ FLAG: Not specifically listed under the Misuse of Drugs Act 1971 as of available data. The UK MDA 2024 circular (21 substances added) does not appear to list 2-FDCK individually — requires verification.**

### Canada
- Covered under blanket NPS provisions (Controlled Drugs and Substances Act, Schedule II analogue provisions). [Web sources; requires legislative verification.]

### European Union
- Detected in 22 EU Member States; controlled in at least 5 (Italy, Latvia, Sweden confirmed; Belgium blanket ban) as of the 2024 EU proposal (EUR-Lex COM(2024)2 [Ref 19]). International Schedule II placement now applies to all signatory states.

### Netherlands
- Specifically banned as of February 2026, removing it from research chemical market availability. [Web sources.]

### Australia
- Detected in Australian drug markets [Ref 17, Ref 25]. Specific scheduling under the Australian Poisons Standard (TGA Schedule 9) has not been confirmed from available sources. **⚠️ FLAG: Australia-specific scheduling status requires verification.**

### Japan / Singapore / Sweden
- Individually controlled by national legislation (cited in WHO ECDD report [Ref 17] as countries with controls in place prior to international scheduling).

---

## Clinical Trials

**No registered clinical trials found on ClinicalTrials.gov** for 2-fluorodeschloroketamine. A Korean patent application (KR20240093579A) was identified describing 2-FDCK for the treatment of depression including treatment-resistant depression — indicating preclinical development interest, but no formal trial registration was identified.

---

## Community Feedback Analysis

**No community feedback submitted.** The Part A2 section of the brief was empty. Standard evidence hierarchy applied throughout.

---

## Gaps & Flags

The following items require editorial attention or have unresolved uncertainty:

### Safety-Critical Flags

1. **⚠️ No LD₅₀ data:** Exact toxic dosage is unknown for 2-FDCK in any species. The seed data note is confirmed accurate.

2. **⚠️ Interaction severity not substance-specific:** The "lethal" severity designations for Alcohol, GHB/GBL, and Tramadol are class-based inferences. No 2-FDCK-specific drug interaction studies exist. These designations are appropriate conservatively but should be labeled as analogical in prose.

3. **⚠️ Tramadol "lethal" designation:** The mechanism for tramadol lethality is more complex than for pure CNS depressants. It is not a clean respiratory depressant. Editorial review recommended for how to frame this interaction.

4. **⚠️ Dose range/duration data:** All dose and duration values in the seed data are user-report–based. No controlled pharmacological dosing studies in humans have been published. Values should be labeled as such.

5. **⚠️ Blood concentration at overdose vs. therapeutic range:** The three forensic blood concentrations (457, 758, 5885 µg/L from Riess et al. 2024) should NOT be presented as "toxic thresholds" — these are from polydrug contexts and do not establish 2-FDCK-only toxic levels.

### Data Gaps

6. **No published Ki/EC50 values for 2-FDCK** at NMDA receptor, DAT, or sigma-1. All pharmacological receptor claims require disclosure as structural-analog inference.

7. **No controlled human pharmacokinetic studies:** Bioavailability, Tmax, plasma half-life, and CYP interaction data for 2-FDCK in humans are absent from published literature. The 5-day tolerance half-life from seed data has no published source.

8. **Stereochemistry gap:** 2-FDCK is sold as a racemate. No published comparative enantiomeric potency data (S vs R) for 2-FDCK. By ketamine analogy, S-enantiomer is likely more potent at NMDA, but this is unconfirmed.

9. **Bladder/urological toxicity:** No published data on 2-FDCK–specific bladder toxicity. Risk is inferred from the ketamine literature. This should be mentioned as a concern but labeled as analogical.

10. **Australia scheduling:** Specific scheduling under Australian Poisons Standard not confirmed from available sources.

11. **UK MDA listing:** 2-FDCK is covered by the Psychoactive Substances Act 2016 but its individual listing under the Misuse of Drugs Act 1971 requires verification.

12. **SMILES string:** Absent from seed data. PubChem CID 13771618 can be used to generate the canonical SMILES (Canonical SMILES available at https://pubchem.ncbi.nlm.nih.gov/compound/13771618). Generation agent should populate this from PubChem.

13. **PubChem CID:** Absent from seed data. Confirmed as **13771618**.

14. **Self-medication interest:** Holborn et al. (2025) [Ref — self-medication paper from OpenAlex results] documented 2-FDCK use for self-medication of depression and anxiety in an online survey (n=274), indicating awareness of its ketamine-like antidepressant properties among some user communities. No clinical evidence for therapeutic efficacy.

### Cross-Reference Notes

- DCK (deschloroketamine) is both a related compound AND a metabolite of 2-FDCK. When 2-FDCK users test positive for DCK, this may reflect metabolism rather than direct DCK co-use. This forensic distinction is important (Joseph et al. 2023 [Ref 2]; Riess et al. 2024 [Ref 3]).
- 2-FDCK seizures contaminated with traces of DCK (0.4–0.6%) were documented (Joseph et al. 2023 [Ref 2]), consistent with shared synthesis precursors or cross-contamination from container reuse.