Many new antiepileptic drugs have been developed to treat seizure disorders. The established antiepileptic drugs reduce neuronal excitability by promoting sodium channel inactivation, inhibiting T-type calcium channels, or enhancing gamma-aminobutyric acid type A receptor-mediated inhibition. Several of the newer agents employ similar mechanisms, whereas others may enhance gamma-aminobutyric acid-ergic inhibitory systems or inhibit glutamatergic excitatory neurotransmission, and may be neuroprotective or antiepileptogenic.