How Viagra Was Discovered
The discovery of Viagra's usefulness for erectile dysfunction was a fortuitous accident.
The original clinical trials studied its use as a cardiovascular drug under the direction of Ian Osterloh at Pfizer. Researchers were looking to produce a drug that could expand blood vessels and thus treat angina, a heart condition that constricts the vessels supplying the heart. Known as a vasodilator, the drug could potentially open up blood vessels--or so they hoped.
By the early 90s they had succeeded in locating a drug that had what Osterloh describes as a "moderate" effect on the blood vessels of the subjects.
Of only moderate interest at the time, in one of the series of studies, some male volunteers found themselves with erections several days after taking the medication.
Writes Osterloh in his 2007 piece, "How I discovered Viagra," "None of us at Pfizer thought much of this side effect at the time. I remember thinking that even if it did work, who would want to take a drug on a Wednesday to get an erection on a Saturday? So we pushed on with the angina studies."
Simultaneously, scientists were suggesting that erectile dysfunction (ED) might be biologically caused and not just a result of psychological issues, as had been believed up to that time. In fact, researchers discovered, ED is caused by blood's inability to flow quickly enough to the penis, due to narrow blood vessels. Now that issue of constricted blood vessels sounded an awful lot like the situation they'd first been trying to treat-- angina.
That piece of knowledge about ED's cause, put together with more clinical trials where males experienced erections after taking the new drug, made Pfizer do some serious wondering.
The drug's impact on angina was disappointing; they could hardly go to market with it. So, in one of the most succesful re-directions in clinical research, Pfizer quit studying the drug as a cardiovascular treatment and began analyzing how effective it might be as a treatment for ED.
The theory was that the drug would allow the smooth muscles in the penis to relax, which would prevent constriction of the blood muscles allowing the tissue fill up with blood--voila! an erection.
This time the research results were anything but disappointing. Pfizer ran studies on 4,000 men with ED, and 64-72% completed intercourse after taking Viagra, vs. 23% on placebo.
Long years after Pfizer first began research on Viagra as a cardiovascular drug, it knew it had something special. Its application in 1997 to the Food and Drug Administration was rapidly approved based on the solidity of the research; by 1998 Viagra (sildenafil) was approved--not as a heart medication--but as the very first oral treatment for men with ED.
And the money has been rolling in ever since.
Actually, Viagra's heart history came back to help it in Pfizer's push to keep its patent. Originally scheduled to go off patent in March of 2012, Pfizer first extended its rights in a lawsuit until 2019, and then gained an additional 6 months of patent protection for studying the effects of a product containing sildenafil, Viagra's active ingredient, in children with pulmonary hypertension. Because the two drugs share the same active ingredient, the extension applied to both.
Viagra sales peaked in 2008 at over $1 billion in sales.
It's enough to do a heart good.
