anticonvulsant /-kənvul″sənt// [Gk, anti + L, convellere, to shake] , 1. pertaining to a substance or procedure that prevents or reduces the severity of epileptic or other convulsive seizures. 2. an anticonvulsant drug. Hydantoin derivatives, especially phenytoin, apparently exert their anticonvulsant effect by stabilizing the plasma membrane and decreasing intracellular sodium levels; as a result, the excitability of the epileptogenic focus is reduced. Phenytoin prevents the spread of excessive discharges in motor areas and suppresses arrhythmias originating in the thalamus, frontal lobes, and other brain areas. Succinic acid derivatives, valproic acid, and various barbiturates are among the drugs prescribed to limit or prevent absence seizures. Some benzodiazepines are also useful as anticonvulsants. Many of these agents can produce fetal malformations when administered to pregnant women. Also called antiepileptic.
