The FDA is examining reports of blindness among men using Pfizer’s Viagra, and Eli Lilly’s Cialis, an Associated Press report said this morning.
Federal health officials told the news service it is still investigating and has no evidence that the drugs are to blame.
The FDA received 42 reports of the blindness, 38 among users of Viagra and four among users of Cialis. There were no cases reported among users of Levitra, the third approved impotence drug.
The type of blindness reported is called NAOIN, or non-arteritic anterior ischemic optic neuropathy. It can occur in men with diabetes or heart disease, the same conditions that can cause impotence and lead to Viagra use.
A Pfizer spokesman told the AP that the drug maker was in discussions with the FDA about adding a disclosure to Viagra’s label to say that in rare cases, men taking Viagra had developed blindness. The spokesman also said men who take Viagra often have high blood pressure and high cholesterol, which are also associated with the conditions that can cause blindness.
Viagra is the dominant drug in the erectile dysfunction category with a 68 percent worldwide market share. Sales of Viagra rose 5 percent to $438 million in the first quarter of 2005.