AM-251 (drug)

AM-251 (drug)
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard 100.162.062 Edit this at Wikidata
Chemical and physical data
Formula C22H21Cl2IN4O
Molar mass 555.238 g/mol g·mol−1
3D model (JSmol)

AM-251 is an inverse agonist at the CB1 cannabinoid receptor. AM-251 is structurally very close to SR141716A (rimonabant); both are biarylpyrazole cannabinoid receptor antagonists. In AM-251 the p-chloro group attached to the phenyl substituent at C-5 of the pyrazole ring is replaced with a p-iodo group. The resulting compound exhibits slightly better binding affinity for the CB1 receptor (with a Ki value of 7.5nM) than SR141716A, which has a Ki value of 11.5nM, AM-251 is, however, about two-fold more selective for the CB1 receptor when compared to SR141716A.[1] Like SR141716A, it is additionally a μ-opioid receptor antagonist.[2]

See also[edit]


  1. ^ Lan, R; Liu, Q; Fan, P; Lin, S; Fernando, SR; McCallion, D; Pertwee, R; Makriyannis, A. “Structure-activity relationships of pyrazole derivatives as cannabinoid receptor antagonists”. J Med Chem. 42: 769–76. doi:10.1021/jm980363y. PMID 10052983.
  2. ^ Seely, KA; Brents, LK; Franks, LN; Rajasekaran, M; Zimmerman, SM; Fantegrossi, WE; Prather, PL (2012). “AM-251 and rimonabant act as direct antagonists at mu-opioid receptors: implications for opioid/cannabinoid interaction studies”. Neuropharmacology. 63: 905–15. doi:10.1016/j.neuropharm.2012.06.046. PMC 3408547. PMID 22771770.