This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autacoids, Subject name: Pharmacology
[{'content': 'Which of the following agent is not used for treatment of erectile dysfunction? \nSelect and explain. \nA. PGE1, B. Vardenafil, C. Phenylephrine, D. Alprostadil', 'role': 'user'}, {'content': 'Answer: C \nExplanation: for male impotence: Alprostadil(PG E1) injected into the penis causing an erection lasting for 1-2 hrs oral sildenafil/tadalafil can also be given papaverine, yohimbine can be used though rarely ESSENTIALS OF MEDICAL PHARMACOLOGY;7TH EDITION; KD TRIPATHI; PAGE NO 190', 'role': 'assistant'}]