The famous Brazilian footballer Pele may have been the biggest promoter of Viagra, but if it weren't for the people of the industrial town in Wales we might never have known about the drug to solve male potency problems.
Workers at a steel mill in the Welsh town of Merthyr Tydfil, in desperate need of cash, applied for a voluntary medical examination.
However, they could not have imagined that they would participate in research that would change the world.
It wasn't until three decades later that some of them discovered that the drug has since helped millions of men with erectile dysfunction.
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In the early 1990s, the pharmaceutical company Pfizer tested a compound called Sildenafil UK-92,480 that treats high blood pressure and angina pectoris.
It was then that the collaboration between Fezer and the residents of the Welsh town of Merthyr Tydfil was contracted for research.
Idris Price was one of those who signed up to test the new drug in 1992.
At that time, he did not have a permanent job because he was laid off at the steel plant.
"If I lacked money, I would go to a place called Simbek," says Idris.
"We were not told anything about the medicine except that the doctor said it was a pill for angina pectoris and that we could have side effects.
"Many of the participants were nervous about what might happen to them," says Price.
The volunteers, then all young men, were paid to take the UK-92,480 pill three times a day for 10 consecutive days.
"Times were tough for us in the late 1980s and early 1990s, and we tried to make money any way we could," adds Idris in the BBC documentary. BKeeping It Up.
He says that the research money was important for his family, because they had nothing at that time.
"Those funds allowed us to buy additional food, firewood. It was actually easy money that came in handy," says Idris.
But when the research was finished, the most talked about at Pfizer was the drug's side effects.
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How was Viagra discovered?
"Volunteers would come out and say they're uncomfortable, because they're noticing that they're having more erections than usual and they're much more intense than usual," said Dr. Pete Ely, the Pfizer research leader.
It was these serendipitous observations among the medical guinea pigs at Merthyr Tydfil that led them to launch a study on impotence at Pfizer.
Patients with erectile dysfunction were tested at a hospital in Bristol, before a further clinical trial was carried out in 1994 in Swansea.
In the hospital in Swansea, men were treated for diabetes and heart disease, with erectile dysfunction being the most common side effect.
"Pfizer said that only heterosexual men in a stable relationship could participate in the study," said David Price, the trial leader and consultant endocrinologist.
“They were all ordinary lads, married in Swansea. During the testing, erotic films were also shown," he adds.
A device was attached to the penis to monitor the effect of the drug, and the doctors assured the men that they would not interrupt them.
The results of the research in Swansea, as well as in Bristol, were positive.
The authorities at Pfizer quickly realized that they had a medicine in their hands that could change the world.
In fact, the results were so positive that several men refused to return the unused pills.
Pfizer's marketing team then began scrambling to introduce the new pill to the public, while experts pondered whether it would be accepted as "extraordinarily special or catastrophic."
The company was very concerned about promoting what could be described as a sex drug in what they thought was a relatively conservative world.
For this reason, feedback from men who participated in the trials was used for marketing purposes.
"One idea from the research was how deeply impotence affects a man, and another is how much it affects his relationships," said Jennifer Dobler, marketing manager at Pfizer.
"I was deeply moved by what the men said about how much it affected their relationships and how important it was to them," she added.
To boost the promotion, Pfizer received a religious blessing from the Vatican, explaining that Viagra could help strengthen the institution of marriage and family values.
Viagra appeared on the shelves of pharmacies in the United States and Great Britain in 1998, as the first approved drug for erectile dysfunction.
It quickly became the fastest selling drug in history with annual sales peaking in 2008 at nearly two billion dollars.
But Idris was unaware of his fellow volunteers' role in the viagra story until the documentary's researchers told him earlier this year.
"I was stunned when I found out," Idris said.
"Viagra is a big thing now... I'm glad the idea was conceived in Merthyr Tydfil," he adds.
Dr David Brune, who worked on Viagra research, says if it weren't for the men from South Wales, the drug might not even exist.
"They made history," he said.
"They were probably just desperate to make a bit of money, but they made a big difference to a lot of people's lives and they should feel good about it," he added.
How common is erectile dysfunction?
The National Health Service in Great Britain says that erectile dysfunction is "very common, especially in men over 40".
Some studies estimate that it may affect half of all men between the ages of 40 and 70.
Long-term studies suggest that by 2025, 322 million men worldwide could be affected by erectile dysfunction.
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