All of the following agents are used for prophylaxis of migraine, except

Prophylaxis of a migraineThe drugs approved by the FDA for the prophylactic treatment of a migraine include propranolol, timolol, sodium valproate, topiramate, and methysergide (not available in the United States).Also amitriptyline, noriptyline, flunarizine, phenelzine, gabapentin, and cyproheptadine.Onabotulinum toxin type A for a chronic migraine.Phenelzine and methysergide are usually reserved for recalcitrant cases because of their serious potential side effects.Ref: Harrison; 19th edition