Amauromine is a neutral antagonist of the cannabinoid (CB) receptor CB1 that is selective for CB1 (Ki = 178 nM; Kb = 66.6 nM) over CB2, with no activity at CB2 receptors at concentrations up to 10 μM. It is also an antagonist of GPR18 (IC50 = 3.74 μM). Amauromine has vasodilatory activity.