10 Accidental Inventions You Won't Believe

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When you think of side effects, you usually consider them to be bad. But in some cases, as we'll soon find out, certain side effects can lead to substantial discoveries.

When Simon Campbell and David Roberts, two researchers working at the pharmaceutical company Pfizer, began studying the effectiveness of a new drug, they had no clue what their product would turn into. The two developed a drug they hoped would treat high blood pressure and a heart condition called angina. By the late 1980s, it was ready to be tested on human patients in clinical trials.

The team administered the drug -- called UK-92480 -- to patients in a trial and learned that it wasn't as effective as researchers predicted. Yet as scientists looked at the side effects of the trial, they noticed multiple patients reporting that the treatment led to erections. With an open mind, researchers at Pfizer moved forward to learn more about this unintended side effect.

Rather than using the drug experimentally to treat blood pressure and heart issues, the company launched a new clinical trial to use the drug for erectile dysfunction disorder. The trial proved successful, and the newly named Viagra, also known as sildenafil citrate, was approved by the U.S. Food and Drug Administration in 1998.

Viagra may spice up lackluster relationships, but our next accidental invention has the ability to mend a broken heart. Read how on the following page.