Potent neuropeptide Y (NPY) Y5 receptor antagonist (IC50 values are 5.4, > 1000, > 10 000 and > 10 000 nM at Y5, Y1, Y2 and Y4 receptors respectively) that displays no affinity for a wide range of other receptors. Does not produce a conditioned taste aversion, suppress sodium appetite or cause pica in rats. Significantly inhibits NPY-induced feeding but not through blockade of Y5 receptors.