Chronic pain is
rampant.
Nearly one third of Americans suffer from
it, and as a nation we spend about $100 billion annually
trying to get relief from it, says Daniela Salvemini,
associate professor of pharmacological and physiological
science at St. Louis University.
Salvemini has been studying pain for some
time and her research, several years ago, led to the discovery
that the production of a certain molecule plays an important
role in the development of pain and inflammation. It's called
peroxynitrite, and it's created when the body experiences all
types of pain including acute inflammatory pain, arthritic
pain and pain from nerve injury. Peroxynitrite is also
produced, in the brain and spine, with prolonged use of
opiates such as morphine.
The increase in peroxynitrite leads to the
development of morphine-induced antinociceptive tolerance,
which means that higher doses of the drug are needed to
achieve adequate pain relief, Salvemini says. The higher doses
lead to side effects such as constipation, nausea and
respiratory depression.
"So the consensus is that chronic use
of morphine causes pain and that this pain masks the
pain-relieving effects of morphine. It appears to be key in
the development of opiate tolerance," she says. "If
we can specifically target peroxynitrite and eliminate it,
we'll have remarkable improvement in treating chronic pain.
And we'll also ameliorate tolerance to morphine and allow it
to act properly without side effects."
Salvemini and Neumann have been looking for
what she calls a "super potent molecule" to destroy
peroxyinitrite and says they have a few that look promising.
Recently, the National Institutes of Health
awarded Salvemini a $975,000 grant to study ways to rid the
body of peroxynitrite. She and Bill Neumann, a chemist at
Southern Illinois University-Edwardsville, have begun
synthesizing and testing synthetic molecules that target
peroxynitrite in rats.
"I don't think we'll have something
that will be the one single answer," she says. "Pain
is very complex, and we'll probably always need a
combination."
They've found that when combined with
non-steroidal drugs, such as ibuprofen, or opiates, such as
morphine, the drugs are able to be more effective. The
reasoning goes that this in turn should lead to fewer or no
side effects from the drugs, because patients will need far
lower doses.
Salvemini is confident that one day, a whole
new class of painkillers will exist to use alone and in
conjunction with traditional remedies for pain management.