PEAQX is a competitive antagonist at the NMDA receptor. Although originally described as 100-fold selective for GluN1/GluN2A receptors vs. GluN1/GluN2B receptors, more detailed studies of the Ki of PEAQX revealed it only shows a 5 fold difference in affinity for GluN1/GluN2A vs. GluN1/GluN2B receptors. It is also a potent anticonvulsant in animal tests.
^Frizelle PA, Chen PE, Wyllie DJ (September 2006). "Equilibrium constants for (R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) acting at recombinant NR1/NR2A and NR1/NR2B N-methyl-D-aspartate receptors: Implications for studies of synaptic transmission". Molecular Pharmacology. 70 (3): 1022–32. doi:10.1124/mol.106.024042. PMID16778008.
^Auberson YP, Allgeier H, Bischoff S, Lingenhoehl K, Moretti R, Schmutz M (April 2002). "5-Phosphonomethylquinoxalinediones as competitive NMDA receptor antagonists with a preference for the human 1A/2A, rather than 1A/2B receptor composition". Bioorganic & Medicinal Chemistry Letters. 12 (7): 1099–102. doi:10.1016/s0960-894x(02)00074-4. PMID11909726.