Seven patients with refractory seizure disorders and neuropsychiatric
symptoms believed secondary to felbamate are presented. Five were on
concomitant valproic acid (and other agents). Anergia, apathy,
bradyphrenia, and increased irritability were prominent. One patient on
felbamate monotherapy had a new-onset psychosis. Felbamate's NMDA receptor
antagonism and GABA potentiation (perhaps enhanced by valproic acid use)
are discussed as possible mechanisms of these side effects.