Beginnings of Sildenafil (aka Viagra)
Nitric Oxide: It’s What Makes Sildenafil / Viagra Work
There was a time, not very long ago, when scientists didn’t think much of nitric oxide. It came as something of a shock when a breakthrough discovery took place that changed the scientific community’s understanding of nitric oxide dramatically.
Today, nitric oxide is recognized as one of the most important molecules produced in humans. In fact, it is commonly referred to as the miracle molecule. It is now understood that nitric oxide acts as a chemical messenger in the body controlling a range of important biological and body functions, including erectile function.
Mention should be made that nitric oxide is particularly important for blood vessel health as it is involved in relaxing the walls of blood vessels, causing vasodilation. (i.e., it causes blood vessels to widen and open up) This is of major importance because wider blood vessels allow for increased blood flow throughout the body and into the heart and other organs. We also know that vasodilation is important for controlling blood pressure. Because nitric oxide in part is involved in the relaxation of blood vessels, it also lowers blood pressure, as dilated blood vessels have a larger diameter which allows blood to flow with lower pressure. In the opposite way, the constriction of blood vessels decreases their diameter and increases blood pressure.
So, how did nitric oxide’s importance come to be understood? To explain, let’s look at the prelude to the breakthrough.
EDRF – the Mystery Element Before Sildenafil or Viagra
In the late 1970’s researchers took up the task of studying vasodilation, and in particular a substance called acetycholine, and its effect on vasodilation. The researchers looked at smooth muscle cells (that surround blood vessels) as they understood that these cells, when relaxed, were responsible for vasodilation. The researchers also looked at endothelial cells that lined the insides of blood vessels. What the researchers found was that blood vessels relaxed only when healthy and functional endothelial cells were present. In other words, without healthy endothelial cells, the smooth muscle cells were not able to relax and cause vasodilation. The question then, that forced itself upon the researchers was – what was the mysterious element produced by the endothelial cells that was required for the relaxation of the blood vessels? One of the complexities that made it difficult to figure out was that the mysterious element was an odd duck – it had a life span of a nanosecond. It would do its job and then disappear, like a biological apparition. All they knew was that it appeared to be some sort of gaseous substance, and as soon as it appeared, the smooth muscle, which surrounds every blood vessel, relaxed. That’s why the researchers chose to name this mysterious element the ‘Endothelium-Derived Relaxing Factor’, or EDRF.
At the same time, yet independently from the EDRF researchers, another scientist, at the University of El Salvador, was working on the same question by studying nitroglycerin. Nitroglycerin was known to ease coronary pain and was commonly given to patients for heart conditions like angina in order to promote vasodilation and increase blood flow to the heart’s muscle. Problem was, no-one knew why the drug worked to relax narrowed vessels.
In 1986, the EDRF researchers figured out the deal – the mysterious element was the gas nitric oxide. For their role in this discovery and their work on “Nitric oxide as a signaling molecule in the cardiovascular system”, the researchers were awarded a Nobel Prize in 1998.
Back to the nitroglycerin researcher. Before the EDRF researchers made their discovery, he discovered that nitroglycerin acted by releasing nitric oxide which in turn was a key chemical in causing the relaxation of blood vessels. So, when the Nobel Prize was awarded jointly to the members of the EDRF group, it resulted in controversy. Part of the criticism came from The University of El Salvador that felt that the Nobel Prize voting body ignored the work of their scientist – Salvador Moncada. Moncada responded that he did not feel snubbed and praised the work of the EDRF group adding that he was happy to have been able to contribute to progress in the field.
A Nobel Prize, Pfizer’s Viagra, and a New Field: Erectile Dysfunction
Not surprisingly, when news of the discovery spread, drug companies began researching ways to enhance or sustain our body’s response to nitric oxide. In 1998, Pfizer came up with a drug based on this that turned out to be unique with a special and unprecedented ability of its own – they called it Viagra. This was the beginning of the next new era of research, and in particular, led to an even larger new field – Erectile Dysfunction.
If you have questions about ED medications, or would like to explore a drug-free option to treat ED, get in touch with us or check out another post of ours on Viagra, Cialis, and Levitra.
