The world's largest drug producer Pfizer Inc. said that its popular impotence treatment Viagra doesn't increase patients' risk of blindness. Pfizer, nevertheless, admitted that it is still working with federal regulators to update the drug's label to reflect rare reports of vision loss, says AP.
Last month, the U.S. Food and Drug Administration reported 38 cases of blindness caused by a condition called NAION or non-arteritic anterior ischemic optic neuropathy among some men who have used Viagra.
Pfizer conducted a review of all post-marketing ocular event reports and concluded that there is no evidence of increased risk of blindness among patients taking Viagra.
The FDA concluded that no causal relationship between Viagra and NAION has been established, but Pfizer has agreed to include on the Viagra label that these reports exist in order to inform physicians and patients. Pfizer said it thought that the Food and Drug Administration had asked for similar information to be included on the labels of all oral erectile dysfunction medicines.
Dr. Joseph Feczko, Pfizer's chief medical officer said, that "men taking Viagra are at no greater risk for blindness—including vision loss from NAION—than men of similar age and health not taking the medicine."
According to Pfizer official statement, NAION, among the most common acute optic nerve diseases in older adults, shares a number of common risk factors with erectile dysfunction: over 50 years of age, high blood pressure, high cholesterol, and diabetes. Pfizer stressed, that since Viagra was introduced in 1998, the company and regulatory authorities around the world have regularly reviewed all reported adverse events, including those involving the eye. No regulatory authority has concluded that Viagra use is associated with an increased risk for blindness. Most of the reported NAION cases occurred in Viagra users with underlying anatomic or vascular risk factors associated with the development of NAION.
The story of Viagra pills starts in 1992 in Great Britain, when the Pfizer company started pharmaceutical research. As a matter of fact, the drug was originally meant to cure some kinds of heart diseases. It soon became clear that Viagra did not help in that field, but it did help to cure another disease: impotence.