Potent and selective mGlu1 receptor negative allosteric modulator (IC50 values are 5.8 and 6200 nM for mGlu1 and mGlu5 respectively). Also acts as an mGlu1 receptor inverse agonist (IC50 = 7 nM) in the absence of ligand. Exhibits no effect at group II/III mGlu receptors. Inhibits L-glutamate-induced increases in intracellular calcium in mGlu1-expressing CHO cells. Inhibits nociceptive behavior, and exhibits anxiolytic and antipsychotic effects in vivo. Orally active. Purity 98%. MW (observed): 358.41