<unk> (injection) is an erectile dysfunction agent that is FDA approved for the treatment of erectile dysfunction due to neurogenic, vasculogenic, psychogenic, or mixed etiology.   Common adverse reactions include penile pain, bleeding, hematoma, ecchymosis, erythema, and penile fibrosis.
Alprostadil 
Iofendylate
Epoprostenol
Bosentan
Endralazine
Guanoxan
Papaverine
Minoxidil 