News :
FDA looking into blindness as possible side effect of
male impotence drugs
FOSTERS ONLINE, July 4 2005 -- Federal
health officials are examining rare reports of blindness among some
men using the impotence drugs Viagra and Cialis, a disclosure that comes
at a time when the drug industry can ill afford negative publicity about
another class of blockbuster medicines.
The Food and Drug Administration still is investigating,
but has no evidence yet that the drug is to blame, said spokeswoman
Susan Cruzan.
This type of blindness is called NAION, or non-arteritic
anterior ischemic optic neuropathy. It can occur in men who are diabetic
or have heart disease, the same conditions that can cause impotence
and thus lead to Viagra use.
The FDA has 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 impotence drug.
"We take this seriously," said FDA's Cruzan.
The FDA is in discussions about the reported cases with
the manufacturers of the three drugs in case there is a problem with
the class of medication and to see if changes need to be made to their
labels.
Eli Lilly & Co., which manufactures Cialis, refers
to vision problems as an uncommon side effect, including seeing a blue
tinge or having difficulty telling the difference between blue and green.
"These are not all the side effects of Cialis," it says on
its Web site.
Viagra manufacturer Pfizer Inc. also refers on its Web
site to some vision issues: "Less common are bluish or blurred
vision, or being sensitive to light. These may occur for a short time."
That language had been available before the current inquiry.
Pfizer spokesman Daniel Watts confirmed Friday that the
drugmaker 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. However, he said there is no proof that Viagra caused the
blindness. He said that men who take Viagra often have high blood pressure
and high cholesterol, which are also associated with the conditions
that can cause blindness.
Levitra is sold in the United States by GlaxoSmithKline
PLC and Bayer AG.
Viagra was approved by the government in 1998. It may aid
in the treatment of enlarged hearts that can result from high blood
pressure, tests on animals indicate.
Levitra was approved in August 2003, and Cialis in November
of that year.
There have been no reports connecting Levitra to blindness,
said Michael Flemming, a spokesman for GlaxoSmithKline PLC. "We
are confident about the safety of our product," said Flemming.
Levitra, Cialis and Viagra all work in the same fashion,
but Flemming said that doesn't mean they all have the same side effects.
"Every drug is different. Every drug is unique," he said.
Analyst Jason Napodano of Zacks Investment Research Inc.
said he doesn't think Viagra sales will stumble because of the new reports
because the number of cases is so small. "It is too early to say
that Viagra is causing this (the blindness) and look how small the numbers
are," he said.
Viagra, approved to treat erectile dysfunction, should
not be used by men with heart conditions whose doctors have warned them
not to have sex. Also, patients taking drugs that contain nitrates have
been warned not to take Viagra because of sudden, unsafe drops in blood
pressure.
The drug's label also warns of erections lasting longer
than four hours, painful erections lasting longer than six hours, headache,
flushed skin and vision problems.
Pfizer Inc. said in its most recent quarterly filing with
the Securities and Exchange Commission that sales of the drug rose 5
percent — to $438 million in the first quarter of the year. Pfizer also
said at the time that Viagra had a 68 percent worldwide market share.
Viagra sales have been under pressure from new competitors
Cialis and Levitra, with revenue sinking 11 percent last year to $1.68
billion from $1.88 billion. Pfizer shares fell in early trading on the
New York Stock Exchange.
Doctors and patients have become increasingly wary of the
downsides of prescription drugs after Merck & Co. yanked its pain
reliever Vioxx from the market last year because of its potentially
lethal side effects.
Merck potentially faces thousands of lawsuits over Vioxx
and analysts have estimated its liability may reach $18 billion.
Pfizer was asked to remove its pain reliever Bextra from
the market because of its side effects and sales of its other arthritis
drug Celebrex are falling. Vioxx, Celebrex and Bextra all fall into
a category of drugs known as Cox-2 inhibitors.
Industry critics have been demanding that drug companies
conduct more post-marketing studies in order to do a better job of discovering
side effects once drugs hit the market.
For more than two decades, Americans have mostly pressed
for quicker approval of what they hope can be lifesaving drugs for such
diseases as AIDS and cancer. But many now are wondering if medicines
— a $200 billion industry annually — are coming out too fast and doing
too much harm.
Viagra also is at the center of controversy over Medicaid's
payment for prescriptions of the drug to convicted sex offenders in
New York and other states.
(source : www.fosters.com)
