Breakthrough for Parkinson's?
by Joshua Lucas
3:00 a.m. 5.Oct.99.PDT
New technologies are being developed
that will allow researchers to pump drugs
straight into the brain in an effort to help
treat Parkinson's disease symptoms and
to study how that disease -- and other
nervous system conditions -- deteriorate.
Read ongoing Med-Tech coverage
The procedure, developed at the
University of Kentucky, could reintroduce
several promising drugs that had been
shelved because the molecules in many
orally administered or traditionally
injected drugs are not able to move from
the bloodstream to the brain.
The drugs contain proteins designed to
improve the function of degenerated
nerve cells.
"We expect clinical treatments based on
targeted delivery of drugs to specific
sites in the brain to become increasingly
commonplace over the next decade," said
Dr. Greg Gerhardt, leader of the
University of Kentucky research team.
Research will start with a modified
Medtronic pump -- a type of pump that
can be implanted and programmed to
deliver drugs into the bloodstream. The
modification will allow drugs to be pumped
directly into brain tissue.
Currently, the Medtronic SynchroMed
Infusion System is only approved to
deliver drugs into the fluid surrounding
the spinal cord in patients suffering
cancer pain and severe muscle
deterioration. It can also be used to
deliver chemotherapy to treat colorectal
cancer that has spread to the liver.
Instead of creating potential harm by
cutting into broad patches of the brain,
the pump technology, aided by an MRI,
can administer drugs into precise
locations.
The advantage of delivering the drugs
directly into the brain is that the process
bypasses the blood-brain barrier. This
barrier is difficult for many of the
compounds within drugs to cross, causing
some drugs to be deemed ineffective for
treating certain diseases.
Also, direct delivery of drugs to the brain
will limit drug-related side effects since
the compounds will only go to areas with
degenerated tissue.
Parkinson's disease is caused by
progressive deterioration of the nerve
cells of that part of the brain controlling
muscle movement.
Dopamine, one of the substances cells
use to transmit impulses, is normally
produced in this area. Without dopamine,
the nerve cells cannot properly transmit
messages from the body, which results in
the loss of muscle function.
Symptoms of Parkinson's range from
tremors and stiff limbs to a distinctive,
shuffling gait. Depression and impaired
ability to think also may develop.
Although treatment with the drugs
levodopa and carbidopa can restore
almost-normal movement to many with
early Parkinson's disease, the treatment
gradually loses effectiveness as the
disease progresses. The research will
focus on patients in the later stages of
Parkinson's in order to learn more about
the deterioration.
The University of Kentucky researchers
will also be working with a protein called
glial cell line-derived neurotrophic factor
(GDNF).
GDNF is a natural growth factor found in
low levels in the adult human brain.
Preclinical studies have shown the protein
protects dopaminergic neurons in the
midbrain.
Protecting these neurons will allow the
brain to continue transmitting messages
to and from muscles in the body.
Use of the Medtronic delivery technology,
however, will not be limited to GDNF. It
will be applicable to a range of drugs that
need to be delivered directly to the brain.
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