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ECS modulator (research)

Unscheduled

AM251

Aliases.AM-251

The reference CB1 antagonist/inverse agonist in the laboratory. 300× selectivity for CB1 over CB2.

Updated on

Level of detail

Identifiers

Formula
C₂₂H₂₁Cl₂IN₄O
Molar mass
555.24 g·mol⁻¹
CAS
183232-66-8
PubChem CID
2125
First described
1996
Origin
Pharmaceutical research (Makriyannis)
InChIKey
BUZAJRPLUGXRAB-UHFFFAOYSA-N

In plain terms

AM251 is used in the laboratory to block the effect of other cannabinoids - an experimental tool. Not marketed.

Receptors and activity

  • CB1
    Ki ≈ 7,5 nMInverse agonist
  • CB2
    Ki ≈ 2290 nMInverse agonist
  • GPR55
    Agonist
  • Agonist
  • Partial agonist
  • Antagonist
  • Modulator
  • Inverse agonist

Hover over a row for the precise value (Ki, EC50…)

Subjective signature

Hover over an axis to read its definition.

  • Calm
    25
  • Clarity
    60
  • Sleep
    25
  • Appetite
    15
  • High
    20

Editorial estimate, not clinical.

Pharmacology

AM251 is the iodinated analogue of rimonabant developed by the Makriyannis group (Lan et al., J Med Chem 1999, PMID 9925732). A selective CB1 antagonist / inverse agonist (Ki = 7.5 nM at CB1 vs 2290 nM at CB2; ratio ≈ 305×). The standard pharmacological tool for demonstrating CB1 mediation of an observed effect: if the effect is blocked by AM251, it is CB1-dependent. Note: it is an unexpected GPR55 agonist - do not use it as a « clean » antagonist in studies involving GPR55.

Origin (research tool)

CB1 antagonist / inverse agonist obtained by iodinated modification of rimonabant; organic synthesis (University of Massachusetts)

Structural classification

Class
ECS modulator (research)
Origin
Pharmaceutical research (Makriyannis)
Status
Unscheduled

References

  1. 1.Lan · J Med Chem 1999PMID 9925732

Structured data

InChIKey
BUZAJRPLUGXRAB-UHFFFAOYSA-N
SMILES
CC1=C(N(N=C1C(=O)NN2CCCCC2)C3=C(C=C(C=C3)Cl)Cl)C4=CC=C(C=C4)I
Formula
C22H21Cl2IN4O
Molar mass
555.24 g·mol⁻¹
CAS
183232-66-8
PubChem CID
2125
Machine-readable entry (JSON)

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