FDA Was Told of Viagra-Blindness Link Months Ago
Friday, July 1, 2005
More than 13 months before a scientific journal reported that Viagra had been linked to a rare form of blindness in some men, a Food and Drug Administration safety officer made the same observation from monitoring adverse event reports and told her supervisors that doctors and patients should be warned of the findings.
Her recommendation was well received, she told congressional investigators, but nothing happened. The FDA issued no public notice or proposed changes to the Viagra label. That came only following widespread publicity last month about the journal article and public concerns about the possible blindness-Viagra link.
The safety officer's experience was outlined in a letter last week to FDA Acting Commissioner Lester M. Crawford from Sen. Charles E. Grassley (R-Iowa), who said the agency had moved far too slowly on an emerging safety concern.
Criticism of the FDA's response to potentially harmful drug side effects has been frequent and sharp since Merck & Co. took its popular arthritis painkiller, Vioxx, off the market last fall after studies indicated that it increased the risk of heart attacks and strokes. The FDA has sought to tighten its drug safety oversight since then, but some critics say the agency is doing too little and still puts more emphasis on reviewing and approving new drugs than on safety concerns.
"I am troubled by the FDA's action, or lack thereof, relating to the updating of Viagra's product label," Grassley wrote. He said the agency's Office of New Drugs (OND) had done nothing "despite OND's knowledge of the blindness risks since January 2004 and general agreement among FDA staff last spring that the label should be updated."
Grassley also wrote that the safety officer, whose name was not disclosed, explained the agency's inaction by saying the Office of New Drugs "is under such time pressure to approve new drugs, often safety concerns needed to be 'fit in' where they could."
"What we appear to have here, Dr. Crawford, is yet another example of the 'separate but unequal' relationship" between the Office of New Drugs and the Office of Drug Safety, Grassley wrote.
Researchers remain uncertain whether Viagra and other impotence drugs pose a significant risk of blindness. Pfizer Inc., which makes the drug, says the side effect has not appeared in any of its 103 clinical trials of Viagra -- involving 13,000 patients -- and that the 23 million users have not reported an increased risk of blindness.
Late last month, however, after the possible link was reported in the Journal of Neuro-Ophthalmology, FDA spokeswoman Susan Cruzan said, "We take this seriously, and the FDA is working with the sponsors to make sure the public is aware of this so they can take it into consideration." The journal study examined seven cases where men suffered an unusual form of sudden blindness within 36 hours of taking Viagra.
On Monday, Pfizer said in a statement that it does not believe there is a causal relationship between Viagra and blindness but that it will add information about the possibility to its label. The company said the FDA had asked the makers of all impotence drugs to do the same.
"There is no evidence that Viagra causes blindness or any other serious ocular condition," said Joseph Feczko, Pfizer's chief medical officer. "Men taking Viagra are at no greater risk for blindness . . . than men of similar age and health not taking the medicine."
In all, the FDA has said, 38 Viagra users and five users of other impotence drugs reported a sudden and permanent blindness in one eye called non-arteritic anterior ischemic optic neuropathy, or NAION. In a report Monday, CBS News said that the number is much higher, and that more than 800 patients and doctors have reported eye problems to the FDA after using Viagra over the past four years, with more than 140 cases of partial or total blindness. While these "adverse event" reports do not prove a causal link between the drugs and sudden blindness, drug safety experts look to them for trends and patterns.
This form of sudden blindness is caused by the blockage of blood flow to the optic nerve and is most common in older people, who disproportionately use Viagra. An estimated 1,000 to 6,000 Americans suffer an optic blockage each year.
Grassley's letter said the FDA safety officer first brought her concerns to the Office of New Drugs in January 2004. That was followed by a more formal draft safety "consult" in March 2004 and a final report the next month.
The letter paraphrases internal FDA documents as saying that Pfizer "resisted the FDA's initial request to update the Viagra label to include information about the NAION risks." Pfizer spokesman Mariann Caprino said the company does not comment on its interactions with the FDA. Earlier, another Pfizer spokesman said the company contacted the FDA about the blindness cases in March, after the journal report was published.
Grassley's letter also questions whether the FDA's adverse event reporting system would be capable of detecting NAION cases that might be associated with Viagra. Until now, it said, few doctors who prescribe Viagra would know to ask patients about vision problems, and few ophthalmologists who treat sudden blindness would know to ask about Viagra use. FDA officials said they had no comment on Grassley's letter.
All three impotence drugs on the market, Viagra, Cialis and Levitra, already warn users that the drug can cause minor vision changes that include blurring, sensitivity to light and the presence of a bluish hue. The makers of Cialis, Eli Lilly & Co. and Icos Corp., have voluntarily added a notice about the risk of sudden blindness to their label.