GLUK5 kainate receptor antagonist (IC50 = 130 nM); also blocks recombinant homomeric GLUK7 receptors. Displays 12,700-fold selectivity for GLUK5 over GLUK6. Exhibits no activity at mGlu group I or NMDA receptors at concentrations of up to 10 μM. Apparent KD value is 18 ± 4 nM for depression of kainate responses on the dorsal root.