Pfizer defends Viagra and its safety record

As expected, Pfizer is denying that Viagra has any problems at all and that it needs to do anything beyond changing the label. The company took a similar line of argument about its other two drugs, Celebrex and Bextra, that had similar adverse side effects.

The company says that in a review of 103 Viagra clinical trials involving 13,000 patients, there were no reports of non-arteritic anterior ischemic optic neuropathy (NAION). Outside of clinical trials, Viagra has been used by more than 23 million men worldwide over the past seven years and reports of visual field loss due to NAION are extremely rare. Pfizer argues that, "There is no evidence showing that NAION occurred more frequently in men taking Viagra than men of similar age and health who did not take Viagra."

NAION is the most common acute optic nerve disease in adults over age 50 and it shares a number of common risk factors with erectile dysfunction: age over 50, high blood pressure, high cholesterol, diabetes. Most of the reported cases in which NAION has occurred in men taking Viagra have involved patients with underlying anatomic or vascular risk factors associated with the development of NAION.

Pfizer reports that it is in discussions with the Food and Drug Administration (FDA) to update the Viagra label to reflect these rare ocular occurrences. Pfizer's competitor, Eli Lilly (the maker of Cialis), has already updated its label. While the number of cases arising from Levitra is still small, the manufacturer has been warned in the past about misleading ads for Levitra.

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