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': 'Which of the following agent is not used in erectile dysfunction: \nSelect and explain. \nA. PGE2, B. Vardenafil, C. Phenylephrine, D. Alprostadil', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Alpha blockers are used in erectile dysfunction not alpha\xa0agonists (phenyephrine).\nDrugs useful in the management of erectile dysfuncLion (ED)\n1. Phosphodiesterase inhibitors\n\nSildenafil\nVardenafi\nTadalafil\nUdenafil\n\n2. PGE1 analog - Alprostadil\n3. Aviptadil', 'role': 'assistant'}]