GYKI 52466 is an allosteric AMPA receptor antagonist. It selectively inhibits AMPA-induced inward currents (IC50 = 7.5 µM) over NMDA- or GABA-induced inward currents in primary rat hippocampal neurons at 50 µM but also inhibits kainate-induced inward currents in the same cells (IC50 = 11 µM).2 GYKI 52466 (10 µM) reduces the amplitude of spontaneous excitatory postsynaptic currents (EPSCs) in the same cells. It increases the latency to seizure onset and reduces mortality in a rat model of generalized tonic-clonic seizures induced by 4-aminopyridine (4-AP) when administered at doses of 25 and 50 mg/kg. GYKI 52466 (30 mg/kg) prevents neuronal damage in the CA1 region of the hippocampus in a rat model of global ischemia-reperfusion injury induced by four-vessel occlusion.