Tadalafil
"Got a 30 day sample from my urologist.  For me, this medicine is wonderful.  Am taking lisinopril and lovastatin.  Was concerned if the medicine helped after the first dose.  And am happy to say that it did.  It worked well after about one hour.  But my most intense erection was about after 6 hours.  No side effects to speak of unless you can say my face seemed flush afterwards.  Just assumed it was working.  Do not have a perpetual erection but can feel that I am on the verge of one for a while.  Couldn't be happier."