This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
Which of the following agent is not used in erectiledysfunction: 
Select and explain. 
A. Apomorphine, B. Vardenafil, C. Phenylephrine, D. Alprostadil
C: Phenylephrine
Answer: C: Phenylephrine 
Explanation: Ref; KD Tripathi pharmacology 7th edition page no;303 Drugs used in erectile dysfunction is Androgens : PDE-5 inhibitors; sildenafil, tadalafil, vardenafil PGE1; Alprostadil P papaverine Phentolamine -alpha blocker apomorphine- dopamine agonist Phenylephrine is an adrenergic drug which is contraindicated in erectile dysfunction