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
[{'content': 'NOT of use in bipolar disorder: September 2012 \nSelect and explain. \nA. Carbamazepine, B. Phenytoin, C. Sodium valproate, D. Lamotrigine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Phenytoin Phenytoin It acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels. Aside from seizures, it is an option in the treatment of trigeminal neuralgia in the event that carbamazepine or other first-line treatment seems inappropriate. It is sometimes considered a class lb antiarrhythmic.', 'role': 'assistant'}]