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Blindness Concerns Hit a Stagnating Market

by Rick Mullin
June 6, 2005 | A version of this story appeared in Volume 83, Issue 23


News late last month that federal authorities are investigating the use of Pfizer's Viagra and other impotence drugs for a possible link to a handful of cases of blindness in men only adds woes to a market that may be stagnating.

FDA is acting on 43 reports of blindness caused by non-arteritic anterior ischemic optic neuropathy (NAION) among patients taking drugs for erectile dysfunction. Of these, 38 had taken Viagra; four had taken Cialis, from Eli Lilly and Icos; and one had taken Bayer's Levitra. The number of men taking impotence drugs is estimated at more than 25 million, with about 23 million taking Viagra. The potential world market is estimated at 189 million patients.

The market for these drugs began to sputter in 2004, six years after FDA approved Viagra. Manufacturers reported $2.4 billion in sales, at least $1 billion below analysts' earlier forecasts. Pfizer attributed Viagra's 11% drop in sales last year largely to competition from newcomers Cialis and Levitra.

Analysts cite limited health care coverage for erectile dysfunction drugs and patients' embarrassment about discussing impotence problems with physicians as the primary factors limiting growth.

Pfizer issued a statement claiming there is no evidence showing that NAION occurred more frequently in men taking Viagra than in men of similar age and health who did not take the drug. Pfizer cited 103 clinical trials with 13,000 patients in which no case of NAION was reported.


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