A CGRP receptor antagonist (Ki = 0.77 μM); binds selectively to the human CGRP receptor complex over the adrenomedullin receptor complexes in HEK293 cells (Kis = >100 and 29 μM for CRLR with RAMP2 and 3, respectively); inhibits CGRP-induced cAMP accumulation in HEK293 cells expressing the CGRP receptor complex (IC50 = 2.2 nM); reduces CGRP-induced vasodilation in isolated human meningeal arteries; inhibits vasodilation induced by topical application of capsaicin in rhesus monkeys (EC50 = 127 nM)