Rise of Viagra How a miner's honesty turned a side effect into pharma gold

It was the ultimate serendipitous discovery: a failed heart medication that became a multibillion-dollar erectile dysfunction drug.

- Hannah Devlin

But the blockbuster story of Viagra could have ended differently were it not for the frankness of the Welsh miners who took part in a clinical trial just before the drug was due to be scrapped, according to Viagra's co-inventor.

Speaking before the screening of Men Up, a new BBC drama executive-produced by Russell T Davies about the ordinary middleaged Welsh men who took part in early trials, Dr David Brown said that the drug's unexpected sideeffect was almost overlooked.

"The whole thing could've been totally missed," said Brown, a former medicinal chemist at Pfizer.

"I don't think there would be a drug around if that one miner hadn't put his hand up." Brown was leading the development of the compound Sildenafil as a potential angina treatment but its prospects were not looking promising, and by 1993 Pfizer had all but decided to abandon the programme.

"They basically said: 'You've wasted money for eight years.

We're going to close it down,"" said Brown, who now runs a company, Healx, which uses Al for drug discovery.