Sunday, April 1, 2012

Viagra Came From What?

Structure of Sildenafil, or "Viagra." IUPAC name: 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-phenylsulfonyl]-4-methylpiperazine.
I wonder why they call it "Viagra."
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Did you know that Sildenafil, "Viagra" in market-speak, was originally developed as a drug to treat hypertension? I just learned this in Biochemistry, and found it pretty interesting. You see, it's all based on a little molecule called nitric oxide, or NO.

In humans, nitric oxide acts as an important signaling hormone in vasodilation, which lowers blood pressure. While it can come from a variety of sources, one way our bodies produce it is by the catalytic activity of NO synthase in the following reaction from arginine to citrulline and NO:
For people with hypertension (high blood pressure), having a drug that can help lower your blood pressure is a very desirable thing. Doctors in England were originally developing Sildenafil to do just that. As it went through drug trials, they noticed that it had the unique side effect of inducing erections in male test subjects.

Sildenafil enhanced a nitric oxide signaling pathway in the penis, resulting in inhibition of a specific phosphodiesterase. Phosphodiesterases degrade cyclic guanosine monophosphate (cGMP), which does a ton of very important things in tissues all over the body. In the penis, it helps regulate blood flow. So, more cGMP, more blood flow. When Sildenafil inhibits phosphodiesterase expression, cGMP levels rise, and you have a marketable treatment for Erectile Dysfunction (ED). Since Sildenafil was the first drug of this kind that could be delivered in pill form, they slapped a label on it and started making awkward commercials to air during Sunday afternoon Nascar races and Monday night football games.

Interesting how so many medical discoveries and inventions in general are nothing more than coincidence and mistakes...

1 comment:

addison said...

I think the best piece of advertising they did was including the warning about have an erection that lasts longer then 4 hours. that really got peoples attention and i think a lot of guys were hoping for that side effect

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