Cannabinoids produce biochemical and pharmacological effects by interacting with the central cannabinoid (CB1) and peripheral cannabinoid (CB2) G protein-coupled receptors. AM630 is a selective CB2 receptor antagonist that binds to CB1 and CB2 receptors with Ki values of 5.2 µM and 31.2 nM, respectively. AM630 behaves as an inverse agonist at CB2 receptors, attenuating the antinociceptive effects of a number of cannabinoids, and as a weak partial agonist at CB1 receptors.