http://www.treatments-for-erectile-d...tion-aids.php3
"Penile Injections: Papaverine Hydrochloride and Phentolamine.
Erections can be achieved by injecting medication directly into the corpora cavernosa (the two chambers that run down the length of the penis and which trap the blood necessary for erections). Penile injections work in as little time as five to fifteen minutes, and the erection may last as long as an hour."