This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sexual Disorders, Subject name: Psychiatry
[{'content': 'Which drug is used in intracavernous injection for erectile dysfunction? \nSelect and explain. \nA. Epoprostrenol, B. Alprostadil, C. Sildenafil, D. Tadalafil', 'role': 'user'}, {'content': 'Answer: B \nExplanation: AlprostadilQ contains naturally occurring prostaglandin E and, hence has vasodilator action. It can be injected into corpora cavernosa or administered intraurethrally. The firm erection is produced within 2 to 3 minutes and may last for 1 hour. Other injectable medications for erectile dysfunction include: Papaverine Phentolamine', 'role': 'assistant'}]