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Impotence drug
Viagra may encourage blood platelets to clump, an occurrence
that may explain why some men have suffered from heart attacks
after taking the drug, according to a new study.
Though clumping
of platelets is necessary for normal blood clotting and to
protect against blood loss during injury, such clumping is
also a factor in causing heart attack and stroke.
Viagra works by
increasing levels of cyclic guanosine monophosphate (cGMP),
a compound in cells. While cGMP was previously thought to
inhibit platelet clumping, researchers say that the compound
actually promotes clumping by causing platelets to become
stickier.
This finding, found
through laboratory experiments of both mouse and human cells,
has led researchers to say that a causal link between Viagra
and cardiac death is possible.
Though further
research is needed, Viagra may also be a risk factor for patients
with pre-existing conditions such as atherosclerosis, researchers
said.
Cell
January 10, 2003;112:77-86
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