A Heart Drug That Took a Surprising Turn
In the late 1980s, researchers at Pfizer were testing a new drug called sildenafil. It was developed to treat angina — chest pain caused by restricted blood flow to the heart. But during early clinical trials in Wales, something unexpected happened: the drug didn’t work well for angina… but male participants reported a very noticeable side effect — frequent and prolonged erections.
Rather than scrapping the project, Pfizer pivoted. The company realized sildenafil might be useful in treating erectile dysfunction (ED), a condition with few effective treatments at the time. In 1998, the drug was rebranded and approved as Viagra, becoming the first oral treatment for ED — and a global sensation.
A heart drug had accidentally become a billion-dollar blockbuster, changing the conversation about male sexual health and launching a new era in pharmaceutical marketing.