T he D ark S ide
of
V iagra
From antivirals to amyl nitrate, nobody knows what a Viagra interaction may lead to by Bob Roehr
ho hasn’t heard of Viagra?
The new male impotence
drug is gamering enough
attention to make a rock star
jealous. It is producing glow
ing testimonials from men who are literally ris
ing Lazarus-like from their marital deathbeds.
Viagra isn’t just for older men who want to
regain their youthful stamina. Diabetes and
other clinical conditions can cause erectile dys
function, while HIV infection and the use of
antiviral and antidepressant drugs may also
cause impotence as a side effect.
Dr. Bill Owen, a San Francisco physician
with a large HIV practice, says in the past
patients and physicians were often reluctant to
bring up matters like erections when they were
confronting an apparent death sentence.
More recently, he says, the success of pro
tease inhibitors has gotten people “to start
thinking about quality of life issues like sexual
function.” He hopes some of his patients will
benefit from Viagra.
But some in the gay community are raising
warning flags about the drug, saying there
remain unanswered questions about possible
drug interactions and concerns about abuse.
The Viagra label warns against using the
product with any nitrate products. The manu
facturer, Pfizer, conducted tests of Viagra with
nitrates used to treat the heart condition angina
and found the combination led to increased
hypertension.
The company did not test Viagra with amyl
nitrate, which is used in recreational inhalants
known as poppers. But Pfizer was concerned
enough about possible side effects that it called
several AIDS treatment advocates and alerted
them to the potential interaction.
Representatives of the Gay and Lesbian
Medical Association met with Pfizer in late
April to discuss issues surrounding Viagra.
Not long after, GLMA issued an advisory
stating, in part: “ ‘Poppers’ act by dilating blood
vessels, and the concurrent use of ‘poppers’ and
Viagra could result in sudden and marked lower
ing of blood pressure, which can be potentially
serious or even fatal.”
Dr. Donald Abrams, an AIDS researcher at
the University of California San Francisco, says,
“People are going to need to just accept that if
they are using Viagra, they should not use pop
pers.”
He dismissed the need for further study, say
ing, “You don’t want to do a research project
that will put people at risk."
Dr. Ken Mayer, an AIDS specialist with the
W
medical school at Brown University, down
played the danger of interactions, in part
“because poppers are pretty short acting.”
He says the worst that is likely to happen is
that a person will pass out.
“The useful thing about passing out is you
faint, you fall, and gravity helps to restore some
of the blood pressure to your brain,” he says. “So
I don’t see how it could cause permanent dam
age.”
No one knows how many people use
inhalants during sex. Some of the products are
illegal.
“It’s all anecdotal,” says Spencer Cox with
the Treatment Action Group. But in his New
York City neighborhood, “At the West Side
Club, everybody carries them, a lot,” he adds.
Hank Wilson, with ACT UP Golden Gate,
believes the use of poppers is increasing.
He worries there are “a lot of doctors who
don’t know that their patients are gay, or that
they use poppers.”
Viagra is metabolized in the liver by the same
enzyme system used by protease inhibitors and
medications such as clarithromycin and keto
conazole.
People on these drugs may maintain Viagra
in their blood longer and at higher levels than
others, but no one knows for sure since those
drug interactions have not been tested.
Pfizer assured GLMA there is little danger
more bo«-'510 y0Ur
from drug interaction—an assertion based on
the company’s estimate of people using Viagra
an average of four times a month.
Still, Abrams and his colleagues at San
Francisco General Hospital are proposing an
interaction study to Pfizer, and the company is
receptive to the initiative. Any data is months
away.
Should Pfizer have run these interaction
tests prior to marketing Viagra?
“We are the community who is pushing for
speedy approval of drugs,” says Ben Schatz,
GLMA’s executive director. “And you can’t pos
sibly get drugs approved with a requirement that
every conceivable interaction be tested.”
Schatz gives Pfizer credit for proactively
approaching the gay community on this issue,
while Abrams notes, “None of the antiviral
companies have bothered to come chat with us
about the products so that we could understand
it and disseminate it widely to our members.”
Currently, GLMA advises patients on med
ications that metabolize through the P450
enzyme system—including protease inhibitors
and some other HIV medications—to begin
with the lowest dose of 25 milligrams of Viagra.
Physicians should monitor for drug interactions
at all dosage levels.
There are other concerns about Viagra as
well. The product produces visual disturbances
in a small percentage of people, who primarily
are mistaking green for blue and have an
increased sensitivity to light—conditions that
last for several hours.
Dr. Michael F. Marmor, a Stanford
University ophthalmologist and spokesman for
the American Academy of Ophthalmology,
points to clinical studies showing a 30 percent
to 50 percent drop in electrical measures of reti
nal function in patients on the drug.
The academy wants more study and urges
patients with retinal eye conditions, such as
macular degeneration or retinitis pigmentosa, to
use Viagra with caution.
Abrams, meanwhile, suggests research into
the possible effects of Viagra when combined
with anabolic steroids and testosterone.
People with more advanced HIV disease may
experience reduced hormone levels
and use replacement therapy as part
of their regimen. Men also use the
hormones illegally to help build
muscles. Abrams says such hor
mones are metabolized differently
from Viagra, but “those agents can
impact on the liver so it is just
another area that should be investi
gated.”
Gay men are surrounded by
images of hard bodies and hard-ons,
the Jeff Strykers of the world who
through the miracles of modem
editing and tape looping appear able
to keep an erection for hours on end.
Schatz sees “a very significant
potential for abuse” of Viagra by “a
segment of our community where
drug use is particularly associated
with sexuality and sexual activity.”
He fears it will be combined with
methamphetamines, which increase
sexual desire but often reduce capac
ity to get or keep an erection.
“People will think, ‘Oh great,
Viagra is an antidote,’ ” he says, adding he wor
ries the combination will lead to increasingly
unsafe sexual practices and the spread of sexual
ly transmitted diseases, including HIV.
Meanwhile, some clinicians have a nagging
fear that consumer desire for Viagra could lead
to a situation like that of fen/phen, a two-drug
treatment intended for extremely obese people
that was ultimately over-prescribed for people
with only minor weight problems.
The drugs were pulled from the market last
year when long-term studies showed they dam
aged the heart.
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