This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'All of the following drugs can worsen angina except: \nSelect and explain. \nA. Dipyridamole, B. Oxyphedrine, C. Thyroxine, D. Sumatriptan', 'role': 'user'}, {'content': "Answer: B \nExplanation: Oxyphedrine is claimed to improve myocardial metabolism so that the hea can sustain hypoxia better. Dipyridamole can cause 'coronary seal' phenomenon - By dilating resistance vessels nonischemic zone as well, it dives the already reduced blood flow away from the ischaemic zone. Sumatriptan causes coronary vasoconstriction. Thyroxine increases sympathetic stimulation (REF. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D TRIPATHI-6th edition.Page No-535)", 'role': 'assistant'}]