Extremely selective, non-peptide NPY Y5 receptor antagonist. Displays > 1000-fold selectivity over Y1, Y2 and Y4 receptors; IC50 values are 1.4, 2765, 7187 and 5637 nM at cloned rat Y5, Y1, Y2 and Y4 receptors respectively. Potently inhibits NPY-induced food intake following i.p. administration in diabetic, free-feeding and fasted rats.