Most people use Sildenafil or Viagra as better known these days but do they really know how this drug is so efficient and so effective? I happened to be a medical student and I chanced upon this drug profile when I was out for research one time and it got my interest as why this drug is so effective and so specific in its actions that it was hard to imagine something to be able to control erectile dysfunction. I discovered that sildenafil actually acts up on an enzyme, the name too complicated to mention here, whose sole responsibility in the body was to control and inhibit blood flow to the penis and since sildenafil acts to inhibit it, it allows increased blood flow to the penis and in turn, helping a person, an impotent one, to achieve his much desired erection and this erection can certainly last up to a maximum of four hours until the drug reaches its max life and it finally gets flushed out of the system. But come to think of it, that is more than enough time for someone to fulfill his sexual desires, even achieve ejaculation and orgasm which is what most impotent men misses. Knowing that fact now, I am entirely convinced that this is a real great discovery in this age and certainly, it will be a long time for any other drug to replace it. Maybe if a cure is drawn in the future, then that will be the time, but for now, sildenafil reigns supreme over ED.