How a Failed Drug Became a Huge Success

This week, I change it up a little and take a break from discussing cybersecurity. Instead, I will discuss how Pfizer accidentally stumbled onto an innovation that has helped many men rise to the occasion. Sometimes, innovation is about being observant.

In the late 1980’s, scientists with the Pfizer Corporation were working on a treatment for angina.  The scientists in Pfizer’s laboratory developed a hypothesis that selectively blocking an enzyme known as phosphodiesterase type five (PDE5) could assist in treating angina [1].  The scientists believed that by blocking PDE5, the patient’s blood vessels might expand and thus treat angina.  The Pfizer team began working on the development of a drug to block PDE5.

Pfizer scientists discovered a PDE5 inhibitor, sildenafil citrate, in 1989.  This medication went by the name of UK-92480 [2].  The early tests of UK-92480 were promising, as the compound seemed to have a moderate effect on the blood vessels of healthy test subjects.  One of the early problems was the short duration of the beneficial effects.  To maintain a constant effect on the blood vessels, the volunteers needed to take UK-92480 three times daily.  Several of the volunteers began complaining of muscle aches from the use of UK-92480.  In one study, some of the male volunteers reported increased erections days after the initial dose.  Pfizer researchers did not think much of the side effects at the time [1].

From Angina to Erectile Dysfunction

While the Pfizer team experimented with UK-92480, another Pfizer scientist, Ian Osterloh, tested for interactions between UK-92480 and nitrates [1].  Since the use of nitrates was the conventional treatment for angina, Osterloh needed to determine if UK-92480 interacted with nitrate treatments.  Osterloh’s test led to the end of UK-92480’s use for treating angina.  The tests showed that UK-92480 amplified the effects of nitrates causing blood pressure to drop dangerously low.  Studies continued reporting volunteers having increased erections as a side effect of UK-92480.  Now that Pfizer ruled out UK-92480 for the treatment of angina, the team led by Osterloh decided to investigate the possible use of UK-92480 in treating erectile dysfunction (ED).

Pfizer realized that UK-92480 held tremendous financial opportunity if the drug proved successful in addressing the need for effective treatment of ED [3].  In attempting to become the first approved oral treatment for ED, UK-92480 faced extensive research and regulatory pressure.  Pfizer needed to test how effective the drug might be in treating ED caused by various medical conditions including high blood pressure, diabetes, heart disease, and prostatectomy.  The results of the initial tests significantly exceeded the expectations.  Next, the drug proved successful in long-term clinical trials involving thousands of men (Osterloh, 2015).  Pfizer applied to the Food and Drug Administration (FDA) for priority approval in 1997 for the drug that Pfizer now called Viagra [3].

In 1998, Viagra became the first FDA-approved oral treatment for ED [4].  To overcome social pressures related to the discussion of ED, Pfizer began an ED awareness media campaign.  The drug company used a campaign aimed at urging men to seek medical advice for ED.  Pfizer sought to remove the stigmatism surrounding discussing ED.  Of course, the campaign also notified men that there was a pharmaceutical solution [3].

Since debuting on the market, Viagra has been a great success.  The Pfizer drug maintains 45% of the market.  In 2012 alone, doctors wrote eight million prescriptions for Viagra.  Total sales of Viagra in 2012 were approximately two billion dollars [2].  The accidental discovery turned into a highly successful product to treat a, until then, mostly ignored medical condition affecting millions of men.

About the author: Donnie Wendt is an information security professional focused on designing and engineering security controls and monitoring solutions. Also, Donnie is an adjunct professor of cybersecurity at Utica College. Donnie is currently pursuing a Doctorate of Science in Computer Science with a research focus on security automation and orchestration.


[1] Osterloh, I. (2015). How I discovered Viagra. Retrieved from Cosmos:

[2] Wilson, J. (2013). Viagra: The little blue pill that could. Retrieved from CNN:

[3] (2016). Viagra: How a little blue pill changed the world. Retrieved from

[4] Fox News. (2008). Discovered by accident, Viagra still popular 10 years later. Retrieved from FoxNews: