D-Leucine ((R)-Leucine) potently terminates seizures even after the onset of seizure activity. D-leucine reduces long-term potentiation but had no effect on basal synaptic transmission in vitro.

D-Leucine failed to compete for binding by cognate ligands in a screen of candidate neuronal receptors, potentially suggesting a novel target. D-Leucine suppressed ongoing seizures at least as effectively as diazepam even at low doses, but without sedative effects. These studies raise the possibility that D-Leucine may represent a new class of anti-seizure agents, and that D-Leucine may have a previously unknown function in eukaryotes[1].