Serendipity Stories bring the practice of serendipity to life in real-world examples.
In the mid-1980s, Pfizer's cardiovascular research team was actively seeking a breakthrough that could save millions of heart patients. The pharmaceutical giant had identified a promising compound that could potentially revolutionize treatment for angina—the crushing chest pain that strikes when the heart doesn't get enough oxygen. Dr. Ian Osterloh, leading the project, felt cautiously optimistic as they moved into human trials with their drug, code-named UK-92,480.
But when Phase II efficacy trials began in 1992, the results were devastating. The compound barely outperformed a placebo. After years of research and millions invested, Pfizer faced an expensive failure. Most companies would have pulled the plug immediately—in pharmaceuticals, failed drugs typically get shelved, their research files sealed and forgotten.
However, Pfizer's culture of meticulous documentation meant nothing went unnoticed—including an awkward observation that would change everything. Dr. David Brown, a soft-spoken investigator running safety trials in Merthyr Tydfil, Wales, had been encountering something odd for weeks. Male volunteers continued to report an unexpected side effect, but Brown felt too embarrassed to mention it in his formal reports.
Finally, during a routine conference call with Pfizer headquarters, he cleared his throat nervously. "There's something else," Brown said hesitantly. "Several participants have mentioned... well, enhanced erections. They're actually asking if they can keep taking the pills after the trial ends."
The line went quiet. This wasn't what anyone had been looking for, but the encounter was undeniable.
Osterloh and his team had been studying cardiovascular medicine for decades—erectile dysfunction wasn't exactly their area of expertise. But in that moment of silence, they began connecting the dots. The drug worked by blocking an enzyme called PDE5, which affected blood flow. If it was improving circulation in one part of the body, perhaps it could work in another.
Instead of viewing the side effect as irrelevant noise, the team began connecting it to a massive unmet medical need. Millions of men suffered from erectile dysfunction in silence, with few effective treatments available.
What happened next was gutsy. Instead of cutting their losses, Pfizer executives made a decision: they would invest another $340 million to start their trials over, this time targeting erectile dysfunction—a condition barely discussed in polite company, let alone boardrooms.
It wasn’t easy, internal debates were fierce. Conservative executives questioned whether Pfizer, known for serious cardiovascular and infectious disease treatments, should risk its reputation on what some dismissively called a "lifestyle drug." Marketing teams worried about advertising something so sensitive. Regulatory experts warned that the FDA might be skeptical of a company pivoting from heart disease to sexual dysfunction.
But Osterloh's team pressed forward, committing to their serendipitous discovery. They redesigned their trials completely, recruiting men with erectile dysfunction instead of heart patients. The results this time were unmistakable—participants reported dramatic improvements, and many pleaded to continue treatment after trials ended.
When the FDA approved Viagra in March 1998, Pfizer had transformed a cardiovascular failure into the fastest-selling drug launch in pharmaceutical history. Within two months, it generated $300 million in U.S. revenue alone. Patients who had suffered in silence for years suddenly had hope restored, relationships rekindled, and confidence rebuilt.
The financial success was staggering—Viagra's net present value eventually exceeded $6 billion. But the real lesson demonstrates how all four serendipity activities must work together. Pfizer was actively seeking solutions, remained open to unexpected encounters, connected seemingly unrelated observations, and had the courage to activate their discovery despite internal resistance.
Today, pharmaceutical companies train researchers on these same serendipity activities: seek broadly, encounter openly, connect creatively, and activate courageously.