Impotence drugs such as Viagra and Cialis can increase the risk of eye damage in men who have a history of heart disease or high blood pressure, researchers said on Tuesday.
In a small study, scientists at the University of Alabama in Birmingham found that men who had suffered a heart attack were 10 times more likely to have optic nerve damage if they had been taking leading anti-impotence pills.
“For patients with a history of myocardial infarction (heart attack), we did observe a strong and statistically significant association suggestive of a link between the use of Viagra and/or Cialis and an increased risk of NAION,” Dr. Gerald McGwin, who headed the study, said in a report in the British Journal of Ophthalmology.
Non-arteritic anterior ischaemic optic neuropathy (NAION), is the most common cause of acute optic nerve disease in people over 50 years old. It can cause permanent loss of vision in one or both eyes.
Viagra, made by Pfizer Inc and Eli Lilly and Co.’s Cialis, are leading impotence treatments.
McGwin and his team questioned 76 men, half of whom suffered from NAION, who were treated at a specialist eye clinic in the United States, about their smoking and drinking habits and use of anti-impotence pills.
Tens of millions of men have used Viagra and Cialis since the treatments were launched.
In May, the Food and Drug Administration in the United States said it had received more than 40 reports of NAION involving impotence drugs but had not determined whether the treatments were responsible.
Pfizer said a review of 103 Viagra clinical trials involving more than 13,000 patients found no reports of NAION. But the company has changed the label on Viagra to note reports of NAION.
“The labels have been updated,” said a spokesman.
Eli Lilly has also changed its labels on Cialis. No one from the company was immediately available to comment on the new research.
McGwin and his team said patients with heart disease or high blood pressure should be warned about the elevated risk of NAION when taking anti-impotence pills.
“Though NAION is a rare condition, the large number of men using Viagra or Cialis suggests that, should an association truly exist, the incidence of NAION could rise dramatically,” McGwin added.