Pfizer Inc last night said a review of its popular impotence treatment Viagra turned up no evidence of increased risk of blindness among patients taking the erectile dysfunction drug.
Nevertheless, Pfizer said it is in talks with US regulators about revising the Viagra label to reflect rare reports of a serious ocular condition known as non-arteritic anterior ischemic optic neuropathy (NAION) in some men who have used the medicine.
Pfizer said it believes the US Food and Drug Administration has asked that similar information be included in the labels of all oral erectile dysfunction (ED) medicines.
In the lucrative ED market, Viagra competes with Cialis, sold by Eli Lily & Co. and Icos Corp., and Levitra, which is co-promoted by GlaxoSmithKline and Bayer AG.
While the FDA concluded that no causal relationship between Viagra and NAION has been established, Pfizer has agreed with the agency to include the fact of these reports in the Viagra label to help inform physicians and patients, the world's largest drugmaker said.
"There is no evidence that Viagra causes blindness or any other serious ocular condition," Joseph Feczko, Pfizer's chief medical officer, said in a statement.
"Several studies specifically looking into the effect of Viagra in the eye by Pfizer as well as independent ophthalmologic experts found Viagra to have no serious adverse effects on the eye," Mr Feczko added.