An NMDA open-channel blocker (Ki = 1.2 μM at -60 mV) and uncompetitive antagonist with known anti-Parkinsonian, anti-epileptic, anti-stroke, and anti-Alzheimer’s disease properties; 12 μM blocks 90% of NMDA receptor activity and prevents NMDA-receptor mediated neurotoxicity in rat cortical and retinal ganglion cell neurons.