NCIt definition : A dione-type anticonvulsant with antiepileptic activity. Trimethadione reduces T-type
calcium currents in thalamic neurons, thereby stabilizing neuronal membranes, raising
the threshold for repetitive activities in the thalamus and inhibiting corticothalamic
transmission. This decreases the abnormal thalamocortical rhythmicity, which is thought
to underlie the paroxysmal three-cycle-per-second spike-and-wave pattern seen with
absence (petit mal) seizures.;