Neuropsychiatric side effects related to treatment with felbamate.

: 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.