The resulting relaxation of the smooth muscle of the penile arterial walls created an unexpected two-hour erection. Around the same time, Giles Brindley, a British physiologist and research scientist, discovered that injecting the drug phenoxybenzamine into the corpora cavernosa of the penis could produce an erection within minutes. At a meeting in Paris in 1984, New York urologist Dr. Adrian Zorgniotti presented his first case studies of self-injection utilizing a combination of papaverine and phentolamine. The latter drug blocks the action of neurotransmitters that cause vasoconstriction, causing the smooth muscles of the penis to relax. Two years later, Japanese researchers presented evidence that injecting the drug prostaglandin E-1 produced powerful erections.
Most men shudder at the thought.
I tell them it won't hurt, but they don't believe me until they experience it for themselves. After being coaxed into receiving a test injection in the office, most men are pleasantly surprised to learn that it really doesn't hurt. Only 1 to 5 percent of men have this reaction, but it's enough to prevent them from using the drug again. Some men who undergo a radical prostatectomy with one or both neurovascular bundles spared still can't achieve an erection after being injected. The nerves could play a role here but for some it has more to do with the fact that they might have anatomic variations in blood supply to the penis.