Antiepilepsy drug Mechanism of action
barbiturates: primidone (Mysoline, phenobarbital) enhances GABAergic inhibition
carbamazepine (Tegretol, Tegretol-XR, Carbatrol) Inhibits voltage-dependent sodium channels
ethosuximide (Zarontin) Modifies low-threshold or transient neuronal calcium currents
felbamate (Felbatol) Unknown
gabapentin (Neurontin) Unknown
lamotrigine (Lamictal) Inhibits voltage-dependent sodium channels, resulting in decreased release of the excitatory neurotransmitters glutamate and aspartate
phenytoin (Dilantin, Phenytek) Blocks sodium-dependent action potentials; reduces neuronal calcium uptake
valproate (Depakote, Depakote ER, Depakene, valproic acid) Reduces high-frequency neuronal firing and sodium-dependent action potentials; enhances GABA effects

Adapted from: Schachter SC. Treatment of seizures. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 61-74. With permission from Elsevier (

Authored By: 
Steven C. Schachter MD