Clue to mystery Viagra deaths

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Clue to mystery Viagra deaths

Clue to mystery Viagra deaths

 

 

Saturday, 11 January, 2003, 00:00 GMT

 

http://news.bbc.co.uk/2/hi/health/2641857.stm

 

Clue to mystery Viagra deaths

 

 

Viagra has been linked to a number of deaths

 

The mystery behind the deaths of a small number of men taking the anti-impotence

drug Viagra may have been solved by scientists.

Although Viagra has achieved worldwide renown as a highly effective treatment

for impotence, it was originally developed to prevent heart attacks and strokes.

 

Our research suggests Viagra may present a risk for patients with

pre-existing conditions

 

 

 

Professor Xiaoping Du

 

The drug was thought to work not only by dilating the blood vessels, but also by

stopping tiny solid particles in the blood called platelets from clumping

together and forming clots that could block blood flow and trigger a heart

attack or stroke.

 

However, new work by researchers from the University of Illinois at Chicago has

found that the drug in fact has the reverse effect - it stimulates the clumping

of platelets, thus raising the risk of clotting.

 

Lead researcher Professor Xiaoping Du said: " Viagra, by itself, probably is not

sufficient to cause a heart attack in healthy people, but our research suggests

that it may present a risk for patients with pre-existing conditions such as

atherosclerosis. "

 

Effect on cells

 

The researchers tested the effect of Viagra on platelets taken from normal

donors.

 

Alone the drug did not stimulate the platelets to stick together.

 

But it did if other compounds found in the bloodstream when the blood vessels

are damaged - such as when somebody is suffering from heart disease - were

added.

 

In fact, under these conditions Viagra caused the platelets to clump together at

concentrations well below those found in patients prescribed the drug as an

impotence treatment.

 

Viagra acts on platelets by inhibiting the breakdown of a compound found in

cells called cyclic guanosine monophosphate (cGMP).

 

For 20 years scientists have thought cGMP acts to stop platelet clumping.

 

But the Chicago researchers believe that in fact cGMP initially causes platelets

to clump together to seal a wound, only later reversing its effect to stop an

excessive build-up that might block a blood vessel.

 

In most circumstances, they argue this would work well.

 

But a person at risk may already have blood vessels narrowed to the point that

even the initial clumping of platelets could be enough to cause problems.

 

Safety record

 

Joel Morris, a spokesman for Pfizer, which makes Viagra, told BBC News Online

that the drug had been shown to have a very impressive safety record.

 

" We take this research seriously, and it will be scrutinised by our medical

teams.

 

" But a recent study by the Drug Safety Research Unit in the UK of 9,000 patients

found that men who take Viagra are at no greater risk of heart problems than the

general population. "

 

It is estimated that 20 million men worldwide have taken Viagra.

 

The research is published in the journal Cell.

 

 

 

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purely speculation or someone's opinion. Always consult with a qualified health

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