Dione anticonvulsants reduce T-type calcium currents in thalamic neurons, including thalamic relay neurons. It does so via the inhibition of voltage dependent T-type calcium channels. This raises the threshold for repetitive activity in the thalamus, and inhibits corticothalamic transmission. Thus, the abnormal thalamocortical rhythmicity, which is thought to underlie the 3-Hz spike-and-wave discharge seen on electroencephalogram(EEG) with absence seizures, is dampened.
Paramethadione and trimethadione are anticonvulsants indicated in the control of absence (petit mal) seizures that are refractory to treatment with other medications. Dione anticonvulsants are used in the treatment of epilepsy. They act on the central nervous system (CNS) to reduce the number of seizures.
Symptoms of overdose include clumsiness or unsteadiness, coma, dizziness (severe), drowsiness (severe), nausea (severe), and problems with vision.