AM 251 is a potent CB1 receptor inverse agonist, with an IC50 of 8 nM at CB1 and 306-fold selectivity over CB2 receptors. AM 251 is also a GPR55 agonist with an EC50 of 39 nM and a µ-opioid receptor antagonist with a Ki of 251 nM. AM251 displays anorectic, antidepressant-like and analgesic effects in animals. AM251 can attenuate or reverse the nociceptive - hyperalgesia and allodynia - behaviours induced by burn injury.