- OTTAWA (CP) -- Health Canada
is advising men who take drugs for impotence and erectile dysfunction to
seek immediate medical attention if they experience vision problems.
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- Users of Viagra, Cialis and Levitra are at risk of a
rare side-effect called nonarteritic anterior ischemic optic neuropathy,
or NAION, caused when blood flow to the optic nerve is blocked.
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- Symptoms include sudden and painless loss of vision in
one or both eyes. Those who experience one episode are at greater risk
of experiencing a second episode affecting the other eye.
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- While in some cases the condition may improve over time,
it can also be irreversible.
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- Men older than 50 or those suffering from heart disease,
high blood pressure, high cholesterol, diabetes or certain pre-existing
eye problems, and smokers, are most at risk.
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- Health Canada cited an article in the March issue of
the Journal of Neuro-Ophthalmology that discussed 14 cases of the eye affliction
occurring in patients using Viagra. All the patients had other risk factors,
including high blood pressure, high cholesterol or diabetes.
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- Health Canada is reviewing two Canadian reports of vision
problems in patients using Viagra that may be consistent with the affliction,
but it said it has not yet confirmed whether those problems are related
to use of the medications.
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- "It is difficult to determine whether the use of
Viagra, Cialis or Levitra is causing (eye problems), as individuals who
have erectile problems often have high blood pressure, diabetes or other
conditions that put them at increased risk," it said in the statement
Tuesday.
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- Health Canada said it is monitoring the drugs and has
requested additional safety information from all three manufacturers -
Pfizer (Viagra), Eli Lilly (Cialis), and Bayer AG/GlaxoSmithKline (Levitra).
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- "Changes to the product information for health-care
professionals and patients are anticipated, and the information will be
communicated to the public after all the safety data has been thoroughly
assessed," said the statement.
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- Last month, Pfizer Inc. said a review concluded that
Viagra doesn't increase patients' risk of blindness but the company was
still working with U.S. federal regulators to update the drug's label to
reflect rare reports of vision loss.
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- In May, the U.S. Food and Drug Administration said it
had 38 reports of blindness caused by NAION among users of Viagra. It also
reported there were instances of the eye affliction among those taking
Cialis and Levitra.
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- Pfizer said it conducted a review of all post-marketing
ocular event reports and concluded there is no evidence of increased risk
of blindness among patients taking Viagra.
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- While the FDA concluded that no causal relationship between
Viagra and NAION has been established, Pfizer agreed to include on the
Viagra label that these reports exist to inform physicians and patients.
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- Similar U.S. measures were expected with Cialus and Levitra.
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