The Discovery of Viagra

Most people think, that there was an intense search for a medicine that could treat erectile dysfunction, but the truth is, Pfizer scientists were very surprised, when their research of a medicine, designed to treat a certain heart disease, revealed a strange side effect which now is the main reason for people to buy Viagra. Ian Osterloh, the leading scientist of Pfizer research team told the world, how sildenafil citrate was discovered.

He says, that he started to work on the project in 1980, when he heard, that scientists at Pfizer came up with a new theory of a medicine that blocks an enzyme, called PDE5.

They thought, that this drug might treat angina. By early 90’s the research developed so much, that by that time they discovered a powerful inhibitor of PDE5, which at that time was called UK-92480. Early experiments with the drug showed, that it had a great effect on the blood vessels, but it remained in a body only for a short time. The volunteers that tried the drug tried to take it 3 times a day to keep it’s effect constant, but the drug gave them a side effect – muscle aches.

Some volunteers reported increased erections few days after the initial dose. But then Pfizer scientists ignored this viagra side effects. However, more and more volunteers reported this side effect, and surprisingly at the same time other studies revealed a lot of information about chemical and biological way how erection process works. The scientists understood, that the drug might be able to amplify the effects of sexual stimulation by opening the blood vessels in penis. With such an information Pfizer decided to drop further research a drug to treat angina and started a new one for a drug to treat erectile dysfunction. They started off with tests with men, who had erectile dysfunction problems. They made them watch erotic movies with a device that monitored their penises size and hardness. The results were optimistic.

Unfortunately, they still had too many unanswered questions. In order to get more answers they conducted another experiment. This time there were around 300 patients with ED, some with diabetes, the duration of treatment was four weeks and there were three different dosages. The results were astonishing. The drug worked in a positive way with more than 90% percents of patients. There were only few patients that reported side effects.

The hardest point of drug development, after such a successful experiment, was ahead.

Pfizer had to do a long term clinical trial with thousands of patients. It required millions of dollars and still had a slim chance of being approved for a license. In 1997 Pfizer finally applied for a license from authorities. After 12 years of studies Viagra was in drugstores shelves.

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