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Research tools

Ibipinabant

A very selective synthetic CB1 antagonist / inverse agonist; muscle toxicity in dogs, phase IIb trial withdrawn.

Unscheduled
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.

C₂₃H₂₀Cl₂N₄O₂S

CAS 464213-10-3

Family
ECS pharmacological toolAntagonist or inverse agonist
Molar mass
487.40 g/mol

Updated on

In plain terms

Ibipinabant is a laboratory molecule with no link to hemp: it was made to block the CB1 receptor, the very one THC activates. It was studied in the 2000s as a possible treatment for obesity and type 2 diabetes. Muscle toxicity was seen in dogs, a registered phase IIb trial was withdrawn, and the molecule is now only a research tool.

Receptors and activity

Target network

CB1Inverse agonistKi = 7.8 nM · human[3H]CP-55940 displacement, CHO cells expressing human CB1
  • Blocks or inhibits
  • Binds or modulates

The lower the cited value, the closer the target sits to Ibipinabant: 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 Ibipinabant.

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. CB1Inverse agonistKi = 7.8 nM · human68 out of 100

    Lange et al., J Med Chem 2004 (ChEMBL values from the document) (new tab) · [3H]CP-55940 displacement, CHO cells expressing human CB1

  2. CB2Binding (function not established)Ki = 7.9 µM · human18 out of 100

    Lange et al., J Med Chem 2004 (ChEMBL values from the document) (new tab) · [3H]CP-55940 displacement, CHO cells expressing human CB2 (selectivity of about 1,000-fold for CB1)

  3. SUR1 KATP channelModulatorno measured value cited
  4. Adenine nucleotide translocase (ANT)Inhibitorno measured value cited
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

At the human CB1 receptor, ibipinabant binds with an affinity of 7.8 nM and about a thousand times more weakly at the CB2 receptor (7,943 nM); the literature calls it an antagonist (Lange et al. 2004) or an inverse agonist (Lynch et al. 2012). It has a high brain-to-plasma concentration ratio (Lange 2004). In diabetic Zucker rats it lowered fasting glucose by 61% and preserved pancreatic islet mass independently of weight loss (Rohrbach et al. 2012); other work shows that part of these metabolic effects goes through a partial opening of SUR1 potassium channels, hence a route foreign to CB1 (Lynch et al. 2012). Muscle toxicity appeared in a six-week preclinical study in dogs, with a rise in 19 plasma acylcarnitines proposed as markers (Zhang et al. 2010), and was then traced to inhibition of the adenine nucleotide translocase, hence of mitochondrial ADP/ATP exchange (Schirris et al. 2015). The phase IIb trial registered by Solvay in obese patients with type 2 diabetes (NCT00541567) was withdrawn; no clinical efficacy data were found. The molecule survives only as a pharmacological tool, with a recent lead for antibacterial repositioning, at the preclinical stage in mice (Dove et al. 2026).

Key sources.

History

Source
An entirely synthetic molecule. It is produced neither by hemp nor by the human body, and has never been isolated from a natural product. It was built in the laboratory as a drug candidate against obesity and type 2 diabetes, then abandoned before any marketing.

Origin

Research tool

No biological route exists for this molecule: ibipinabant is a product of organic synthesis belonging to the diarylpyrazoline class, with no plant precursor and no enzymatic intermediate. Hemp does not make it, and it appears in no natural cannabinoid profile.

Classification

Family, origin and source verification

Family

ECS pharmacological tool › Antagonist or inverse agonist

Verification

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

Wikipedia (English)

Ibipinabant (new tab)

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

  1. Lange JHM et al., J Med Chem 2004: 3,4-diarylpyrazolines, CB1 antagonists (original publication on SLV319) (new tab)PMID 14736243
  2. Schirris TJJ et al., Sci Rep 2015: inhibition of mitochondrial ADP/ATP exchange and myotoxicity of ibipinabant (new tab)PMID 26416158
  3. Zhang H et al., Anal Chem 2010: acylcarnitines in dogs treated with ibipinabant (new tab)PMID 20387806
  4. Rohrbach K et al., Diabetes Obes Metab 2012: beta-cell loss in the diabetic Zucker rat (new tab)PMID 22268426
  5. Lynch CJ et al., Am J Physiol Endocrinol Metab 2012: SUR1 KATP channel openers (new tab)PMID 22167524
  6. Chorvat RJ et al., Bioorg Med Chem Lett 2012: peripherally acting CB1 blockers related to ibipinabant (new tab)PMID 22959249
  7. Janero DR & Makriyannis A, Expert Opin Emerg Drugs 2009: cannabinoid receptor antagonists (new tab)PMID 19249987
  8. Dove AS et al., Antimicrob Agents Chemother 2026: ibipinabant and Neisseria gonorrhoeae (new tab)PMID 41636526
  9. ClinicalTrials.gov NCT00541567: phase IIb trial of BMS-646256, sponsor Solvay, status withdrawn (new tab)
  10. PubChem, compound record CID 9826744 (ibipinabant) (new tab)

Identifiers

Names

IUPAC name
(4S)-5-(4-chlorophenyl)-N-(4-chlorophenyl)sulfonyl-N'-methyl-4-phenyl-3,4-dihydropyrazole-2-carboximidamide
Other names
BMS-646256 · SLV319 · SLV-319

Identifiers

Formula
C₂₃H₂₀Cl₂N₄O₂S
CAS
464213-10-3
PubChem CID
9826744(new tab)
InChIKey
AXJQVVLKUYCICH-OAQYLSRUSA-N
SMILES
CN=C(NS(=O)(=O)C1=CC=C(C=C1)Cl)N2C[C@@H](C(=N2)C3=CC=C(C=C3)Cl)C4=CC=CC=C4

Machine-readable entry (JSON)

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