RCS-8
A phenylacetylindole with a cyclohexylethyl chain, an analogue of JWH-250, a narcotic in France by generic clause.
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.
C₂₅H₂₉NO₂
CAS 1345970-42-4
- Family
- Synthetic CB receptor agonistNew psychoactive substance
- Molar mass
- 375.50 g/mol
Updated on
In plain terms
RCS-8 is a synthetic cannabinoid made in a laboratory. It does not exist in hemp and has nothing to do with cannabidiol. It binds to the same receptors as THC, with a measured affinity stronger for CB2 than for CB1. In France it falls under the narcotics list by way of a chemical-family clause.
Receptors and activity
Target network
- Activates
The lower the cited value, the closer the target sits to RCS-8: 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 RCS-8.
CB1CB1 found in 7 regions of the body
- Basal gangliadenseMost dense in basal ganglia outflow nuclei1
- CerebellumdenseVery dense in the cerebellum1
- HippocampusdenseVery high concentrations in the hippocampus2
- AmygdaladenseHigh concentrations in the amygdala2
- CortexpresentPresent throughout the neocortex2
- Adipose tissuepresentExpressed in adipose tissue3
- GutpresentColonic epithelium, smooth muscle and plexus4
Map sources
- Herkenham M et al. Cannabinoid receptor localization in brain. Proc Natl Acad Sci U S A, 1990 (new tab)
- 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)
- Engeli S et al. Activation of the peripheral endocannabinoid system in human obesity. Diabetes, 2005 (new tab)
- Wright K et al. Differential expression of cannabinoid receptors in the human colon: cannabinoids promote epithelial wound healing. Gastroenterology, 2005 (new tab)
Cited values
- CB1AgonistKi = 81.3 nM · human51 out of 100
Hess et al. 2016, Forensic Toxicol (new tab) · competitive [3H]CP55,940 binding, CHO cell membranes
- CB2AgonistKi = 14.6 nM · human64 out of 100
Hess et al. 2016, Forensic Toxicol (new tab) · competitive [3H]CP55,940 binding, CHO cell membranes
Pharmacology
RCS-8 is a phenylacetylindole: 1-[1-(2-cyclohexylethyl)indol-3-yl]-2-(2-methoxyphenyl)ethanone. It is described as the analogue of JWH-250 in which the pentyl chain on the indole nitrogen is replaced by a 2-cyclohexylethyl group, everything else (acetyl bridge with an intercalated methylene, methoxy group in the ortho position) remaining identical. On human receptors expressed in CHO cells, Hess et al. (2016) measured Ki values of 81.3 nM at CB1 and 14.6 nM at CB2, and observed activation of both receptors in a cAMP assay. The United States listed it by name in Schedule I in 2012 (Synthetic Drug Abuse Prevention Act, Public Law 112-144). Wohlfarth et al. (2014) note that no metabolism study existed for this already-scheduled phenylacetylindole: in human hepatocytes and with high-resolution mass spectrometry, they identified more than 20 metabolites (oxidation, demethylation, glucuronidation) and designated as major analytical targets the glucuronide of hydroxyphenyl-RCS-8, several glucuronides hydroxylated both on the cyclohexyl and on the phenyl ring, unconjugated hydroxyphenyl-RCS-8 and the glucuronide of demethyl-hydroxycyclohexyl-RCS-8. No controlled study in human beings was found.
Key sources.
- Wohlfarth A, Pang S, Zhu M, Gandhi AS, Scheidweiler KB, Huestis MA. Metabolism of RCS-8, a synthetic cannabinoid with cyclohexyl structure, in human hepatocytes by high-resolution MS. Bioanalysis. 2014;6(9):1187-1200 (new tab)PMID 24946920
- 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
- Logan BK, Reinhold LE, Xu A, Diamond FX. Identification of synthetic cannabinoids in herbal incense blends in the United States. J Forensic Sci. 2012;57(5):1168-1180 (new tab)PMID 22834927
- Hutter M, Kneisel S, Auwärter V, Neukamm MA. Determination of 22 synthetic cannabinoids in human hair by liquid chromatography-tandem mass spectrometry. J Chromatogr B. 2012;903:95-101 (new tab)PMID 22835826
- Public Law 112-144 (9 July 2012), title XI, subtitle D, s. 1152: Synthetic Drug Abuse Prevention Act of 2012, naming of « SR-18 and RCS-8 » in Schedule I (new tab)
- Council Framework Decision 2004/757/JHA, consolidated version of 12.01.2026 (annex: substances subject to Union control) (new tab)
History
- Source
- A wholly synthetic molecule, absent from hemp and from every living organism. It was identified among the synthetic cannabinoids of commercially available « herbal incense » products in the United States (Logan et al. 2012) and is one of the 22 compounds included in a hair assay designed for users of « Spice »-type smoking mixtures (Hutter et al. 2012). 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 phenylacetylindoles.
Legal framework
- European Union
It does not appear in the annex to Framework Decision 2004/757/JHA (consolidated version of 12 January 2026), which names only five synthetic cannabinoid agonists: MDMB-CHMICA, ADB-CHMINACA, CUMYL-4CN-BINACA, MDMB-4en-PINACA and 4F-MDMB-BICA. Nor does it appear in annex III of the consolidated ANSM list (tables I and II of the 1971 Convention on Psychotropic Substances). Outside the Union, it is listed by name (« SR-18 and RCS-8 ») in Schedule I of the US Controlled Substances Act by the Synthetic Drug Abuse Prevention Act of 2012 (Public Law 112-144, subtitle D, approved 9 July 2012).
- France
A narcotic in France by generic clause, not by name: the consolidated ANSM list (updated 16 February 2026) does not cite RCS-8. Its annex IV covers any molecule of the indol-3-yl methanone family bearing on the indole nitrogen a substituent of the alkyl, haloalkyl, halobenzyl, alkenyl, cycloalkylmethyl, cycloalkylethyl, methyl-oxane, 1-(N-methylpiperidin-2-yl)methyl or 2-(4-morpholinyl)ethyl type, and on the carbon of the methanone bridge a naphthyl, benzyl, phenyl, cyclopropyl or adamantyl group, substituted or not. Literal reading: RCS-8 bears a 2-cyclohexylethyl group (a cycloalkylethyl) on the nitrogen and a 2-methoxybenzyl group (a substituted benzyl) on the carbonyl carbon; the same list names neighbouring phenylacetylindoles under this clause (JWH-167, JWH-201, JWH-250, JWH-251). Characterisation by generic clause remains more fragile before a court than a listing by name.
Sources: EUR-Lex, UNODC, CND, ANSM, IUPHAR/BPS, ChEBI, EUDA. Our method.
Classification
Family, origin and source verification
- Family
Synthetic CB receptor agonist › New psychoactive substance
- Class
phenylacetylindole
- Verification
Classification, sources and binding values checked on 20 October 2026; text read against its sources and Wikipedia.
- Wikipedia (English)
Article paired by the molecule's structure (InChIKey), revision read on 19 October 2026. Read as a second opinion, never cited as a source.
References
- Wohlfarth A, Pang S, Zhu M, Gandhi AS, Scheidweiler KB, Huestis MA. Metabolism of RCS-8, a synthetic cannabinoid with cyclohexyl structure, in human hepatocytes by high-resolution MS. Bioanalysis. 2014;6(9):1187-1200 (new tab)PMID 24946920
- 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
- Logan BK, Reinhold LE, Xu A, Diamond FX. Identification of synthetic cannabinoids in herbal incense blends in the United States. J Forensic Sci. 2012;57(5):1168-1180 (new tab)PMID 22834927
- Hutter M, Kneisel S, Auwärter V, Neukamm MA. Determination of 22 synthetic cannabinoids in human hair by liquid chromatography-tandem mass spectrometry. J Chromatogr B. 2012;903:95-101 (new tab)PMID 22835826
- Public Law 112-144 (9 July 2012), title XI, subtitle D, s. 1152: Synthetic Drug Abuse Prevention Act of 2012, naming of « SR-18 and RCS-8 » in Schedule I (new tab)
- 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-[1-(2-cyclohexylethyl)indol-3-yl]-2-(2-methoxyphenyl)ethanone
- Other names
- SR-18 · BTM-8
Identifiers
- Formula
- C₂₅H₂₉NO₂
- CAS
- 1345970-42-4
- PubChem CID
- 53394099(new tab)
- InChIKey
- BSQFBMXCQIKYNI-UHFFFAOYSA-N
- SMILES
- COC1=
CC= CC= C1CC(= O) C2= CN(C3= CC= CC= C32) CCC4CCCCC4
LLM ingestion format: a structured superset of the entry (identifiers, binding, versioned legal status). Full corpus.