<unk>  is a phosphodiesterase 5 inhibitor that is FDA approved for the treatment of erectile dysfunction, benign prostatic hyperplasia.   Common adverse reactions include flushing, indigestion, nausea, backache, myalgia, headache, nasopharyngitis, respiratory tract infection.
Tadalafil
Avanafil
Vardenafil
Finasteride
Ingenol mebutate
Oxybutynin 
Gemeprost
Treprostinil 