Competitive NMDA receptor antagonist that displays moderate selectivity for NR2A-containing receptors (Ki values are 0.13, 0.47, 1.10 and 3.86 μM for GluN2A, GluN2B, GluN2C and GluN2D subunits respectively). Please refer to IUPHAR Guide to Pharmacology for the most recent naming conventions. MW (observed): 251.22.