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
Which of the following antiepileptic does not cause OCP failure 
Select and explain. 
A. Phenytoin, B. Valproate, C. Carbamazepine, D. Phenobarbitone
B: Valproate
Answer: B: Valproate 
Explanation: Because Sodium Valproate is an enzyme inhibitor, whereas other antiepileptics are enzyme inducers which can lead to OCP failure.