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': 'Drugs used in prophylaxis of a migraine are all except? \nSelect and explain. \nA. Propranolol, B. Flunarizine, C. Topiramate, D. Levetiracetam', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Prophylaxis of migraine is required if the attacks are frequent (>2-3 per month). The drugs useful for prophylaxis are:\n\nPropanolol is the most commonly used drug for prophylaxis of migraine attacks. Timolol, atenolol, metoprolol and nadolol can also be used but the drugs with ISA (e.g. pindolol) are ineffective.\nCalcium channel blockers like flunarizine (also blocks Na+ channels) is also effective\nMethysergide, cyproheptadine and TCAs like amitriptyline can also be used.\nClonidine can be used orally for the prophylaxis of migraine attacks.\nTopiramate (anticonvulsant drug) has recently been approved for prophylaxis of migraine. Valproate and gabapentin also possess some prophylactic activity.', 'role': 'assistant'}]