D. Felbamate

Felbamate has a broad spectrum of anticonvulsant action. The drug has multiple proposed mechanisms including 1) blocking voltage-dependent sodium channels, 2) competing with the glycine-coagonist binding site on the N-methyl-D-aspartate (NMDA) glutamate receptor, 3) blocking calcium channels, and 4) potentiating the action of GABA. It is an inhibitor of drugs metabolized by CYP2C19 and β-oxidation, and induces drugs metabolized by CYP3A4. It is reserved for use in refractory epilepsies (particularly Lennox-Gastaut syndrome) because of the risk of aplastic anemia (about 1:4000) and hepatic failure.