ACCIDENTAL CURES

TREATMENTS discovered by serendipity. This week: Viagra

DOCTORS in the UK issue around 1.7 million prescriptions a year for Viagra. But the impotence drug started life as a potential treatment for angina, which constricts vessels supplying the heart with blood.

Drug firm Pfizer was trying to develop a medicine to improve blood flow in angina patients by making muscles in the blood vessel walls relax, dilating them and allowing more blood to reach the heart. Initial results proved disappointing and the company was about to scrap the drug when reports emerged of a side-effect in male patients on the drug — an increase in the number and quality of erections. Tests on penile tissue showed that, after Viagra, was administered, blood vessels in the tissue relaxed, allowing more blood to flow into the tissue, triggering an erection. In 1998 Viagra became the world’s first tablet for erectile dysfunction, offering an alternative to therapies such as vacuum pumps or saline-filled implants.