Potent and selective non-competitive mGlu5 antagonist that displays inverse agonist properties; blocks mGlu5 constitutive activity in vitro (IC50 = 87 nM). Acts at an allosteric modulatory site shared with MPEP and binds the mGlu5 receptor with Kd values of 54 and 31 nM for rat and human receptors respectively. Displays anxiolytic activity following oral administration in vivo; also exhibits analgesic properties.