Felbamate-d4 is intended for use as an internal standard for the quantification of felbamate (Item No. 18000) by GC- or LC-MS. Felbamate is an inhibitor of NMDA receptors and a modulator of GABAA receptors that also has broad-spectrum inhibitory activity against excitatory amino acid receptors.1,2,3 It binds to NMDA channels with dissociation constants of approximately 200, 110, and 55 µM in the resting, activated, and desensitized states, respectively, and inhibits NMDA currents in a use-dependent manner.1 Felbamate is a positive modulator of α1β2γ2S, α1β3γ2S, α2β2γ2S, and α2β3γ2S subunit-containing GABAA receptors expressed in X. laevis oocytes, with negative modulation of GABAA receptors containing the subunits α1β1, α1β3γ2L, α4β1γ2S, α4β3γ2S, and α6β1γ2S.2 It inhibits seizures induced by maximal electroshock, pentylenetetrazole (Item No. 18682), and picrotoxin (Item No. 20771) in mice (ED50s = 16.3, 5.51, and 5.23 mg/kg, respectively). Formulations containing felbamate have been used in the treatment of severe refractory seizures.WARNING This product is not for human or veterinary use.