A non-competitive, highly potent antagonist selective for mGlu5 receptors (IC50 = 36nM). Also a positive allosteric modulator of mGlu4 and weak anatagonist of nMDA receptors. Biologically active admitted systematically. Widely used in assessing the functional roles of mGlu5 receptors in a variety of research areas, such as learning and memory, sleep, neuroprotection, depression, addiction, anxiety and stress related disorders, analgesia, locomotion, neural plasticity, and Parkinson's disease.