[[[(1S)-1-(4-Bromophenyl)ethyl]amino](1,2,3,4-tetrahydro-2,3-dioxo-5-quinoxalinyl)methyl] phosphonic acid tetrasodium salt

PEAQX, also known as NVP-AAM077; 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.