<prompt> Which of the following agent is not used in erectile dysfunction:PGE2VardenafilPhenylephrineAlprostadil  <response>: Alpha blockers are used in erectile dysfunction not alpha agonists phenyephrine.Drugs useful in the management of erectile dysfuncLion ED1. Phosphodiesterase inhibitorsSildenafilVardenafiTadalafilUdenafil2. PGE1 analog - Alprostadil3. Aviptadil 