Felbamate (2-phenyl-1,3-propanediol dicarbamate) is clinically available for the treatment of refractory epileptic seizures, and is known to modulate several ion channels including γ-aminobutyric acid type A (GABAA) receptors. To determine felbamate subunit selectivity for GABAA receptors we expressed 15 different GABAA receptor combinations in Xenopus laevis oocytes. Felbamate positively modulated GABA-currents of α1β2γ2S, α1β3γ2S, α2β2γ2S and α2β3γ2S, whereas felbamate was either ineffective or negatively modulated the other 11 receptor combinations. Regional distributions of GABAA receptor subunits suggest that felbamate may differentially modulate distinct inhibitory circuits, a possibility that may have relevance to felbamate efficacy in refractory epilepsies.
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