Potent metabotropic glutamate mGlu 1 receptor antagonist (IC 50 = 6.3 μ M at rat mGlu 1a ). Displays ≥ 40-fold selectivity over other receptors: mGlu 5 , mGlu 2 , mGlu 4a (IC 50 > 300 μ M), NMDA and AMPA (IC 50 = 250 μ M). Neuroprotective in cultured murine cortical cells and rat hippocampal slice cultures in vitro . Reduces the volume of ischemia-induced brain infarcts in rats following systemic administration in vivo .