(R)-CPP is an NMDA receptor antagonist (K = 0.14 µM). It binds to NMDA receptors containing GluN2A, GluN2B, GluN2C, and GluN2D subunits with K values of 0.04, 0.3, 0.6, and 2 µM, respectively. It inhibits depolarization induced by NMDA in isolated hemisected frog spinal cord (pA = 6.56) and NMDA-induced sodium efflux from rat brain slices (pA = 6.2). (R)-CPP inhibits the clonic phase of sound-induced seizures in DBA/2 mice (ED = 65.8 µmol/kg) and the myoclonic phase of stroboscopic-induced seizures in P. papio photosensitive baboons (ED = 127 µmol/kg).