There is provided a CRF receptor antagonist comprising a compound of the formula (I): wherein R1 is an optionally substituted hydrocarbyl, an optionally substituted C-linked heterocyclic group, an optionally substituted N-linked heteroaryl group, a cyano or an acyl; R2 is an optionally substituted cyclic hydrocarbyl or an optionally substituted heterocyclic group; X is oxygen, sulfur or —NR3— (wherein R3 is a hydrogen, an optionally substituted hydrocarbyl or an acyl); Y1, Y2 and Y3 are each an optionally substituted carbon or a nitrogen, provided that one or less of Y1, Y2 and Y3 is nitrogen; and Z is a bond, —CO—, oxygen, sulfur, —SO—, —SO2—, —NR4—, —NR4-alk-, —CONR4— or —NR4CO— (wherein alk is an optionally substituted C1-4 alkylene and R4 is a hydrogen, an optionally substituted hydrocarbyl or an acyl); or a salt thereof or a prodrug thereof.