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': 'An attack of migraine can be easily terminated by: \nSelect and explain. \nA. Acetylcholine, B. Ergotamine, C. Morphine, D. Ibuprofen', 'role': 'user'}, {'content': 'Answer: B \nExplanation: SPECIFIC ANTIMIGRAINE DRUGS\nErgotamine:\xa0It is the most effective ergot\xa0alkaloid for migraine. Given early in attack,\xa0lower doses generally suffice, and relief is\xa0often dramatic. However, when pain has become severe-larger doses are needed and control\xa0may be achieved only after few hours. Oral/sublingual route is preferred. 1\xa0mg is given at\xa0half hour intervals till relief is obtained or a\xa0total of 6 mg is given. Parenteral administration, though rapid in action is more hazardous.\nErgotamine acts by constricting the dilated\xa0cranial vessels and/or by specific constriction\xa0of carotid A-V shunt channels. Ergotamine\xa0and\xa0DHE have also been shown to reduce neurogenic inflammation and leakage of plasma in\xa0duramater that occurs due to retrograde stimulation of periascular afferent nerves. These\xa0actions appear to be mediated through partial\xa0agonism at 5-HTID/IB receptors in and around\xa0cranial vessels.\nReference: Essentials of Medical Pharmacology Eighth Edition KD\xa0TRIPATHI\xa0page no 193\u200b', 'role': 'assistant'}]