Reversible corticotropin releasing factor receptor 1 (CRF1) antagonist (Ki values are 3.4 and 7.9 nM at rat and human CRF1 respectively) that displays >1000-fold selectivity over CRF2 receptors. Suppresses CRF-induced ACTH release in vitro (IC50 = 241 nM) and is brain penetrant.