Viagra developer dies at 92

Robert Furchgott, the Nobel prize-winning scientist whose research on a gas's effect as a blood vessel relaxant paved the way for revolutionary impotence treatments such as Viagra, has died at age 92.

The pharmacologist died last Tuesday in the northwestern city of Seattle, his daughter told yesterday's New York Times.

Research led by Furchgott and colleagues Louis Ignarro and Ferid Murad showed that nitric oxide -- known primarily as an air pollutant from cigarettes and car engines that contributes to smog -- plays a vital role in the human cardiovascular system and regulating blood pressure and circulation.

The three researchers earned the Nobel prize for physiology in 1998, with the Swedish academy stressing it was the first time scientists proved the critical effects of a gas on biochemical functions in the human body.

The discovery of the effect of nitric oxide, a colorless and odorless gas, on the relaxation of blood vessels marked a key step in laboratory company Pfizer's development of the erectile dysfunction drug sildenafil, which it markets under the name Viagra.

The little blue pill was approved by the US Food and Drug Administration in 1998 as a treatment for erectile dysfunction and became enormously popular, bursting perceived social taboos of treating such a condition, with some 35 million men worldwide using the drug.