Ethosuximide ( see structure)  is a succinimide  anticonvulsant, used mainly in absence seizures. Ethosuximide is considered the first choice drug for treating absence  seizures in part because it lacks the idiosyncratic hepatotoxicity of  the alternative anti-absence drug Valproic acid. There is some controversy over the exact mechanism by which ethosuximide  prevents absence seizures. While the view that ethosuximide is a T-type  calcium channel blocker gained widespread support following its  proposal, attempts to replicate the initial finding were inconsistent.
Now researchers, lead by Dr. Tracy A. Glauser, Director of Comprehensive Epilepsy Center at Cincinnati Children's Hospital Medical  Center, have come up with an interesting finding, i.e., ethosuximide (Zarontin), one of the oldest anti-seizure medications  is most effective at controlling what is  called absence or "petit mal" epilepsy, with the fewest side effects.  Valproic acid (Valproate, Depakote) came second, and the newest drug,  lamotrigine (Lamictal), was third.
The study included children aged 2.5 to 13 years, newly diagnosed  with epilepsy and free of other problems, such as autism. They were  randomly assigned to one of the three drugs. The study measured  primarily whether they were free of seizures without intolerable side  effects after 16 weeks, with a few children continuing for as long as 20  weeks. The study also measured how the drugs affected the children's  ability to pay attention.
Ethosuximide prevented seizures in 53 percent of the children,  slightly less than the 58 percent freedom-from-failure rate of valproic  acid but significantly better than the 29 percent for lamotrigine. But  only 33 percent of those taking the older drug had significant attention  problems, compared to 49 percent of those taking valproic acid, the  researchers found. 
Researchers conclude that, it was somewhat unexpected that the oldest of the drugs had as good an  effect as the other and better side effects &  the study highlights the importance of looking not only at seizure control  but also how the child does otherwise....... 
Ref : http://www.cincinnatichildrens.org/about/news/release/2010/epilepsy-trial-3-4-2010.htm
