Tue 26 Jul 2005
The Globe and Mail (Canadian Press)reports:
Ottawa — Health Canada is advising men who take drugs for impotence and erectile dysfunction to seek immediate medical attention if they experience vision problems.
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.
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.
While in some cases the condition may improve over time, it can also be irreversible.
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.
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.
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.
“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.
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).
“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.
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.
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.
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.
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.
Similar U.S. measures were expected with Cialus and Levitra.
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