Very potent and selective, non-competitive antagonist of the human glucagon receptor (hGR). Binds with high affinity to human GR (IC50 = 3.7 nM), and moderate affinity to murine and canine GRs (IC50 values are 63 and 60 nM respectively). In contrast, displays poor affinity for rat, guinea pig, and rabbit glucagon receptors (IC50 > 1 μM). In functional studies, inhibits glucagon-stimulated cAMP synthesis in CHO cells expressing hGR (IC50 = 41 nM), and in murine liver membranes. Orally active in vivo.