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Synthetic

5F-MN-18

The fluorinated analogue of MN-18, a high-affinity indazole carboxamide, scheduled as a narcotic in France.

Narcotic: named in schedule
Level of detail

Harm-reduction warning

No characterised human dose: animal / in vitro data only. Effect profile, safety margin and acute toxicity are not documented in human clinical practice. Extremely potent compound: severe effects, seizures and deaths reported in the literature.

C₂₃H₂₂FN₃O

CAS 1445581-91-8

Family
Synthetic CB receptor agonistNew psychoactive substance
Molar mass
375.40 g/mol

Updated on

In plain terms

5F-MN-18 is a synthetic cannabinoid made in a laboratory, spotted in Japan in 2014. It does not exist in hemp and has nothing to do with cannabidiol. It binds very strongly to the cannabinoid receptors in laboratory assays, and it is classified as a narcotic in France.

Receptors and activity

Target network

CB1AgonistKi = 1.7 nM · humancompetitive [3H]CP55,940 binding, CHO cell membranes
  • Activates

The lower the cited value, the closer the target sits to 5F-MN-18: one ring per factor of 100. A target with no measured value stays on the edge.

Where these targets live

Where each target has been found in humans, according to the cited studies. The map shows the target, not an effect of 5F-MN-18.

Brain, side view
Body, front view
Blood

CB1CB1 found in 7 regions of the body

  1. Basal gangliadenseMost dense in basal ganglia outflow nuclei1
  2. CerebellumdenseVery dense in the cerebellum1
  3. HippocampusdenseVery high concentrations in the hippocampus2
  4. AmygdaladenseHigh concentrations in the amygdala2
  5. CortexpresentPresent throughout the neocortex2
  6. Adipose tissuepresentExpressed in adipose tissue3
  7. GutpresentColonic epithelium, smooth muscle and plexus4

Map sources

  1. Herkenham M et al. Cannabinoid receptor localization in brain. Proc Natl Acad Sci U S A, 1990 (new tab)
  2. Glass M et al. Cannabinoid receptors in the human brain: a detailed anatomical and quantitative autoradiographic study in the fetal, neonatal and adult human brain. Neuroscience, 1997 (new tab)
  3. Engeli S et al. Activation of the peripheral endocannabinoid system in human obesity. Diabetes, 2005 (new tab)
  4. Wright K et al. Differential expression of cannabinoid receptors in the human colon: cannabinoids promote epithelial wound healing. Gastroenterology, 2005 (new tab)

Cited values

  1. CB1AgonistKi = 1.7 nM · human80 out of 100

    Hess et al. 2016, Forensic Toxicol (new tab) · competitive [3H]CP55,940 binding, CHO cell membranes

  2. CB2AgonistKi = 2.5 nM · human77 out of 100

    Hess et al. 2016, Forensic Toxicol (new tab) · competitive [3H]CP55,940 binding, CHO cell membranes

Bar length follows the measured value (Ki, Kd, EC50 or IC50), on one scale shared by every entry, from 100 µM to 0.1 nM. A target with no cited value has no bar.

Pharmacology

5F-MN-18 is the fluorinated analogue of MN-18, identified with it in Japan in 2014; both compounds were placed on the controlled-substance lists of Japan and a few other countries the same year (Diao et al. 2017). Hess et al. (2016) measure on human receptors Ki values of 1.65 nM at CB1 and 2.50 nM at CB2, with strong activation of both receptors in a cAMP assay. The metabolism study by Diao et al. in human hepatocytes identifies 20 metabolites for this molecule against 13 for MN-18; the three most abundant are 5'-OH-MN-18, MN-18 pentanoic acid and 1-(5-fluoropentyl)indazole-3-carboxylic acid. The first two have lost the fluorine; only the third has kept the fluorinated chain. No controlled study in human beings was found.

Key sources.

History

Source
A wholly synthetic molecule, absent from hemp and from every living organism. It was identified in 2014, with MN-18, in an ongoing survey of new psychoactive substances in Japan (Diao et al. 2017). None of this has anything to do with hemp or with cannabidiol products.

Origin

Laboratory synthesis

No known biosynthetic pathway: the molecule is produced by no plant and no living organism. It is entirely synthetic in origin and belongs to the chemical family of the naphthyl-headed indazole-3-carboxamides.

Classification

Family, origin and source verification

Family

Synthetic CB receptor agonist › New psychoactive substance

Class

indazole-3-carboxamide

Verification

Classification, sources and binding values checked on 20 October 2026; text read against its sources and Wikipedia.

Wikipedia (English)

No dedicated article.

References

  1. Hess C, Schoeder CT, Pillaiyar T, Madea B, Müller CE. Pharmacological evaluation of synthetic cannabinoids identified as constituents of spice. Forensic Toxicol. 2016;34:329-343 (new tab)PMID 27429655
  2. Diao X, Carlier J, Zhu M, Huestis MA. Human Hepatocyte Metabolism of Novel Synthetic Cannabinoids MN-18 and Its 5-Fluoro Analog 5F-MN-18. Clin Chem. 2017;63(11):1753-1763 (new tab)PMID 28821542
  3. Council Framework Decision 2004/757/JHA, consolidated version of 12.01.2026 (annex: substances subject to Union control) (new tab)

Identifiers

Names

IUPAC name
1-(5-fluoropentyl)-N-naphthalen-1-ylindazole-3-carboxamide
Other names
5-Fluoro-MN-18 · 5F-MN18

Identifiers

Formula
C₂₃H₂₂FN₃O
CAS
1445581-91-8
PubChem CID
91936859(new tab)
InChIKey
XBSWUIWDRFCAGZ-UHFFFAOYSA-N
SMILES
C1=CC=C2C(=C1)C=CC=C2NC(=O)C3=NN(C4=CC=CC=C43)CCCCCF

Machine-readable entry (JSON)

LLM ingestion format: a structured superset of the entry (identifiers, binding, versioned legal status). Full corpus.