Question:
Erectile Dysfunction Explanation
Answer:
Have you ever noticed the difference between ads for Viagra and those for
other prescription drugs? Most feature a typical patient who explains how a
particular drug works and how it has improved his or her life. Viagra ads
never do that.
After talking with a specialist, I've found out how these drugs work, and in
this column I'm going to share that information with you. If that's not what
you like to read about at breakfast, then turn the page now.
Recent academic studies indicate that erectile dysfunction, or what used to
be called impotence, is still a widespread problem. In the 1950s, 25 percent
of men 60 years or older who participated in Alfred Kinsey's study reported
that they had problems maintaining an erection.
The much more reliable 1994 Massachusetts Male Aging Study, which is the
benchmark in the field, found the problem was even more widespread.
Estimates based on those figures project that erectile dysfunction could
affect as many as 30 million men in the United States.
Those big numbers do not, however, make erectile dysfunction a natural part
of aging, according to Dr. Craig Niederberger. He is the chief of the
andrology division in the Department of Urology at the University of
Illinois at Chicago.
"That's a particularly cruel way of putting it," he said. "Angina is also
associated with aging, but chest pain is not natural. We wouldn't say that
we should not treat chest pain just because lots of people have it."
Aging does cause changes in male sexual function.
"As you grow older, you lose nerve endings in the penis, so sensation wanes.
But that's not a bad thing," Niederberger explained. "Most people ejaculate
very quickly at age 18, but (older males) are able to prolong an erection
much longer due to the change in nerve endings."
Niederberger recently published the Men's Attitudes on Life Events and
Sexuality, or MALES, survey showing that embarrassment and misunderstandings
still stop lots of men from seeking readily available treatments.
"Many people now know that (erectile dysfunction) is a common condition that
affects more than half of all men over age 40, but few understand the close
link between (erectile dysfunction) and its physical causes," he said.
"Compounding this problem is the fact that many men do not seek treatment
because they think the problem is in their head, they feel it is temporary
or they are embarrassed to discuss it."
Despite the buzz about Viagra in recent years, a majority of men still
believes erectile dysfunction is mainly a psychological problem. At least 80
percent of patients with erectile dysfunction have physical problems, but in
Niederberger's survey, 39 percent said their erectile difficulties were
"more psychological than physical."
Some 35 percent said their erectile dysfunction was "just due to stress."
Niederberger discounts such psychological causes and said men should think
of their penis as a thermometer to detect underlying physical problems.
Erectile dysfunction usually indicates that there are other physical
problems. The survey found that men with erectile dysfunction were more than
twice as likely to have diabetes, and 1.6 times more likely to have high
cholesterol and blood pressure. Hypertension also contributes to erectile
dysfunction.
"We all get plaque in the arteries," Niederberger said, "and that means the
penis can lack a blood supply."
Most of these problems can now be solved with a group of drugs named PDE-5
inhibitors (of which Viagra is the most famous example). Any underlying
health problems need to be treated, but the success of these drugs is based
on solving the lack of blood supply.
"It's really cool how your penis works," Niederberger said.
He explained that the penis consists of three cylinders, with two on top and
one on the bottom. The two on top are encased in thick fibers.
Stimulation causes impulses from nerves within these cylinders, which leads
to the release of nitric oxide from nerve endings and cells in the penis.
The nitric oxide increases levels of another substance called cyclic
guanosine monophosphate, or cGMP, which relaxes the muscle that controls
blood flow to the penis. When that muscle is relaxed, the blood flows in and
the penis becomes erect.
PDE-5 is the enzyme that reverses the process. It breaks down cGMP and
allows the blood to flow out of the penis. PDE-5 inhibitors help erectile
dysfunction because they increase the levels of cGMP and allow more blood to
flow to the penis, resulting in an erection.
Niederberger called this "a nuts and bolts approach" to erectile dysfunction
because it focuses on the penis rather than trying to fix systemic problems.
Viagra has had this field to itself, but other products will be coming onto
the market in the near future. Niederberger thinks that some of these new
drugs may be more effective. (Disclosure: Niederberger has been running
clinical trials for vardenafil, which is GlaxoSmithKline's PDE-5 inhibitor.
Also, GlaxoSmithKline funded the MALES study.)
These new PDE-5 inhibitors will work like Viagra, but tests so far suggest
they may work more quickly, and have different "half-lives." Viagra has to
be taken an hour or so before intercourse, and some patients have found that
is a real damper on spontaneity.
Clinical trials show that the new drugs work in as few as 30 minutes, and at
least one may last much longer than the four to five hours that Viagra is
effective.
These may also reduce unpleasant side effects some patients have
experienced, according to Niederberger. The main complaint has been the
feeling that "my head is going to explode." Trials of the newer drugs have
found fewer side effects and greater effectiveness, he said.
Niederberger completely rejects the criticism that the drugs curing erectile
dysfunction pander to the vanity of the baby-boom generation that refuses to
grow old gracefully. He sees no comparison with the growing poularity of
botox, face-lifts and other anti-aging treatments.
"That's cruel," he said. "Sex is an important part of life. Erections are
the product of a healthy body."
