Washington,
DC, May 26, 2005---The U.S. Food and Drug Administration is studying
cases of blindness reported in men using the oral impotency drugs Viagra,
Cialis, and
Levitra. The story
was first reported by CBS
news and confirmed by FDA spokesperson Susan Cruzan, who said that
43 reports of NAION (non-arteritic anterior ischemic optic neuropathy)
had been reported---38 in men using Viagra, 4 using Cialis, and one
using Levitra. Such occurrences, if found to be causally related, would
be an extremely rare complication, considering the tens of millions
of men who have used these drugs since the FDA first approved Viagra
in 1998.
“A definite causal relationship cannot be established at this
time,” said Dr. Howard Pomeranz, a University of Minnesota ophthalmologist
who first reported NAION in a Viagra-user in 2000. A total of 14 cases
of NAION, each occurring within minutes to hours after Viagra ingestion,
was reported by Dr.
Pomeranz in
the March, 2005 issue of the Journal of Neuro-Opthalmology. All
reported cases had atherosclerotic risk factors such as diabetes, hypertension,
or hyperlipidemia. These risk factors are also associated with erectile
dysfunction, the indication for Viagra; however, the close temporal
relationship between onset of blindness and drug ingestion has raised
FDA scrutiny. “We are taking this seriously,” said FDA spokesperson
Cruzan.
Pfizer,
maker of Viagra (sildenafil), has posted to its website the statement
that among 13,000 men in 103 clinical trials, NAION was not observed.
NAION
is the most common acute optic nerve disease, with thousands of cases
reported annually in the U.S. The disorder is associated with swelling
of the optic nerve head, possibly as a result of altered blood flow,
leading to ischemia. NAION is typically heralded by blurred vision and/or
visual field defects, before progressing to complete loss of vision.
The Viagra-class of drugs (PDE-5 inhibitors) have long been known to
have potential ocular side-effects, which are well-described in the
package inserts, but blindness
has not been previously reported.
A
USRF study describing Viagra efficacy vis-à-vis E.D. severity
and partner’s perception was published in 1999.
A
comparison of Viagra, Levitra and Cialis was the subject of a recent
USRF Special Report.
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