Which of the following antiepileptic drugs acts by affecting the levels of GABA?
Sodium valproate
Ethosuximide
Phenytoin sodium
Carbamazepine
Ans. (A) Sodium valproate(Ref: KDT 8/e p444)It acts by various mechanisms like increase in GABA, blockade of Na+ channels and inhibition of T-type Ca2+ currents. Valproate increases the formation of GABA (by stimulating glutamic acid decarboxylase) and inhibits the degradation of GABA (by inhibiting GABA transaminase and succinic semialdehyde dehydrogenase).Phenytoin and carbamazepine acts by affecting neuronal Na+ channels.Ethosuximide acts by affecting T-type Ca2+ currents.
Epilepsy