This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
All of the following antiepileptic agents act Na+ channel except - 
Select and explain. 
A. Vigabatrin, B. Phenytoin, C. Valproate, D. Lamotrigine
A: Vigabatrin
Answer: A: Vigabatrin 
Explanation: Ans. is 'a' i.e., Vigabatrin Mechanism of action of different antiepileptics. Prolongation of Na+ channel inactivation Facilitation of GABA mediated Cl- channel opening Inhibition of T type Ca++ current Decrease of excitatory neurotransmission o Phenytoin o Carbamazepine o Valproate o Lamotrigine o Topiramate o Zonisamide o Barbiturates o Benzodiazepine o Vigabatrin o Valproate o Gabapentin o Tiagabine o Ethosuximide o Trimethadione o Valproate o Felbamale