The invention provides a lactate dehydrogenase inhibitor that makes it possible to suppress refractory epilepsy in which conventional antiepileptic drugs are ineffective, and an antiepileptic drug containing said inhibitor. The lactate dehydrogenase inhibitor of the invention contains a compound represented by formula (III) i.e., isosafrole or a compound having isosafrole as a scaffold, and the antiepileptic drug of the invention has these compounds as an active ingredient.
