Potent, competitive neuropeptide (NPY) Y1 antagonist (Ki = 3.3 nM, IC50 = 5.9 nM) that displays > 47, > 100, > 160, > 160 and > 160-fold selectivity over σ1, α1, Y2, Y4 and Y5 receptors respectively. Reduces food intake and body weight via central Y1 inhibition and is brain penetrant.