11/16 1905 Reno's Announcement Raises Visibility of ...
MINNEAPOLIS, Minn., Nov. 16 /U.S. Newswire/ -- In light of Attorney General
Janet Reno's announcement that she has been diagnosed with Parkinson's disease,
the American Academy of Neurology (AAN) wants to reinforce the need for
increased funding for research of neurological conditions such as Parkinson's.
"While tremendous breakthroughs have been made recently, there is still much
to learn," said the AAN.
According to the AAN an estimated 1 million people in the United States have
Parkinson's disease, a slowly degenerative neurological disorder that doctors
believe is related to a chemical imbalance in the brain. Primary symptoms of
this disease include stiffness, tremor, difficulty in initiating movement and
loss of balance. Parkinson's affects both men and women, generally 40 years of
age or older.
According to Dr. Cheryl H. Waters, a neurologist and a Parkinson's expert at
the University of Southern California, "There are a lot of treatments and a wide
array of medications available to treat Parkinson's disease. However, we need
more research funding to find a cure for this disease."
"Even though there is no cure at this time, people with Parkinson's disease
continue to make valuable contributions to society," the AAN said. Many years
may pass before early symptoms progress to the point where they interfere with
normal activities.
------ Editor's Note: More information and interview opportunities are
available by contacting the American Academy of Neurology at 612-623-8115.
11/16 1838 DRUG THERAPY TO MANAGE PARKINSON'S DISEASE
NEW YORK, Nov. 16 /PRNewswire/ -- More than one million Americans suffer with
Parkinson's disease (PD), a chronic, progressive neurological disorder that
affects motor function, according to the American Parkinson's Disease
Association (APDA). Although there is no cure for Parkinson's disease, there
are prescribed medications that can help minimize the patient's symptoms -- and
perhaps slow the progression -- of the disease.
There are a variety of anti-parkinsonian medications that reduce the severity
of PD symptoms, thereby increasing patient ability to function. The number and
severity of symptoms vary widely among patients, as does individual response to
treatment. Accordingly, physicians may prescribe one of the anti-parkinsonian
medications or a combination, depending upon each patient's condition.
It is very important that open, ongoing communication exists between
physicians and patients, so that together they can determine the most
successful treatment regimen. Patients who ask questions and find out all they
can about the disease will be better able to take control of their disease.
All medications currently used to manage PD have one common effect: to
minimize the imbalance between two chemicals in the brain -- dopamine and
acetylcholine. Balance between the messages from these two chemicals is
necessary for smooth, controllable body movements.
Some anti-parkinsonian treatments may lose their efficacy over time. Usually,
physicians work to control symptoms with small doses of the least powerful
drugs, leaving the more potent drugs for later stages of the disease. Because
treatment is individualized, physicians will constantly change dosages and
combinations of anti-parkinsonian medications over time.
Effects of these drugs can often be complementary when used in combination.
However, some anti-parkinsonian drugs may cause side effects that may be
mistaken for PD symptoms. In all cases, the physician and patient must weigh
the benefits of treatment against the potential side effects when determining
appropriate therapies.
Currently, physicians work with a number of medication categories to control
PD:
Dopamine Replacement
Use of sustained release Sinemet(R) CR (carbidopa/levodopa,
controlled-release)/Sinemet(R) (carbidopa/levodopa) has become the standard
treatment for PD in the United States. Because PD impairs the ability of the
substantia nigra, a tiny patch of cells located on the midbrain, to produce
dopamine, the goal of carbidopa/levodopa therapy is to provide this
neurotransmitter from an outside source. Dopamine is necessary for normal
movement, balance, posture and muscle tone. The drug used for this therapy,
levodopa, when given orally, is converted to dopamine.
Sinemet CR is indicated to help control Parkinson's disease motor symptoms
(e.g., tremor) and may allow PD patients to participate in normal daily
activities. However, because prolonged use sometimes can result in negative
side effects and a "wearing off" phenomenon, many physicians traditionally
withheld Sinemet CR/Sinemet therapy until symptoms worsened.
Levodopa, developed in the 1960s, was the first significant treatment for
Parkinson's disease. It is the same drug neurologist Oliver Sacks, M.D., gave
to his post-encephalitic patients who experienced parkinsonian-like symptoms, as
was dramatized in the film, "Awakenings."
Today, levodopa is given together with carbidopa, whose function is to
inhibit the conversion of levodopa to dopamine outside the brain (e.g., in the
peripheral tissues) so that less levodopa is needed in order to achieve a
pharmacologic effect. The administration of carbidopa and levodopa together
also contributes to a reduction of side effects, such as nausea, which may occur
when levodopa is given alone.
Sustained-release Sinemet(R) CR (carbidopa/levodopa) and Sinemet(R)
(carbidopa/levodopa) are two agents that contain fixed ratios of this
carbidopa-levodopa combination that can maximize the benefits of therapy while
reducing the side effects. The sustained-release formulation was developed to
provide smooth, steady plasma levels of levodopa, thus reducing the motor
fluctuations that are characteristic of PD. In addition, it allows most
patients to take fewer doses per day. The most common side effects of Sinemet
and Sinemet CR are nausea and dyskinesia.
When patients begin dopamine replacement therapy, the effects of a dose of
medication usually last until the next dose is scheduled to be taken. As the
disease progresses, however, some patients begin to experience motor
fluctuations. The use of the sustained-release formula of carbidopa/levodopa
minimizes this phenomenon, which may allow the patient to participate in normal
daily activities.
Preventing Dopamine Breakdown
One of the most recent developments in PD treatment is Eldepryl(R)
(selegiline hydrochloride), also referred to as deprenyl. At the recommended
dosage of 10 mg per day, selegiline is a selective inhibitor of monoamine
oxidase type B (MAO-B).
MAO-B is an enzyme that breaks down the chemical dopamine in the brain.
Eldepryl, as an MAO inhibitor, prevents this breakdown from happening and allows
dopamine to remain available in the brain for a longer period of time. By
blocking the breakdown of dopamine, selegiline prevents a further reduction in
the dopamine supply.
Eldepryl is indicated as an adjunct in the management of Parkinson's disease
patients being treated with Sinemet CR/Sinemet. Eldepryl may help to
control/delay the need for Sinemet CR/Sinemet dose increases, while maintaining
functional ability over time. By controlling Sinemet CR/Sinemet dose increases,
Eldepryl will help minimize Sinemet-related side effects and extend the length
of time Sinemet CR is effective. Minor side effects of selegiline include
nausea, dizziness, and dyskinesia (involuntary movements).
In addition, the breakdown of dopamine by MAO-B can lead to the formation of
byproducts called free radicals. Free radicals are a normal part of human
metabolism but, in excess, they may actually lead to the destruction of
dopamine-producing neurons in the brain, thus worsening parkinsonian conditions.
By blocking MAO-B and slowing dopamine breakdown, selegiline may prevent the
formation of free radicals and potentially slow the death of dopamine-producing
neurons.
(The role of free radicals in PD is not yet proven and theories are based
upon published scientific data. Data supporting the role of selegiline in
slowing the loss of neurons are from an ongoing laboratory study. Eldepryl is
not indicated to slow the loss of neurons and clinical relevance of data
continues to be investigated.)
Reducing Acetylcholine Messages
Anticholinergics target the chemical acetylcholine, a neurotransmitter that
helps send messages within the brain and throughout the body. While scientists
know that acetylcholine assists the function of muscles and some organs such as
the heart, they don't fully understand this chemical's role in the brain. It is
known that acetylcholine acts as an excitatory substance in the brain -- too
much of this transmitter leads to message transmission rates that are above
normal levels.
Anticholinergics are usually the first medications prescribed in the
treatment of PD. These medications may control symptoms effectively for the
first three months after diagnosis, and may help some patients for up to two
years. Studies demonstrate anticholinergic therapy works for fifty percent of
PD patients, usually improving symptoms -- mainly tremor and rigidity -- by 30
percent.
By blocking the action of acetylcholine, anticholinergics reduce tremor and
rigidity by compensating for the lack of dopamine in the brain. Some side
effects can include dry mouth, blurry vision, dizziness and digestive problems
and some patients find that these agents often are ineffective in controlling
bradykinesia or walking and balance problems. Commonly used anticholinergics
include Artane(R) (trihexyphenidyl HCL), Cogentin(R) (benztropine mesylate) and
Symmetrel(R) (amantadine HCL).
Stimulating Dopamine
Dopamine agonists are medications similar enough to dopamine to mimic its
action and stimulate neurotransmission directly, sending messages to the body to
move. There are two dopamine agonists available for PD treatment -- Parlodel(R)
(bromocriptine mesylate) and Permax(R) (pergolide mesylate).
Clinical studies show that when dopamine agonists are prescribed in
combination with levodopa/carbidopa, symptoms may improve from 10 to 50
percent. Traditionally, dopamine agonists have been used to supplement
carbidopa/levodopa. The medications may also delay or prevent long-term
carbidopa/levodopa side effects.
Side effects of bromocriptine are orthostatic hypotension (a drop in blood
pressure usually experienced by the patient as dizziness), nausea, as well as a
tendency toward confusion and hallucinations. Side effects of pergolide are
dyskinesia, nausea, dizziness, confusion and hallucinations.
Future Therapies
One therapy that recently has gained attention is the use of fetal tissue
implants. This experimental and controversial surgery involves the
transplanting of fetal substantia nigra cells into the PD patient's brain. The
hope is that these cells will become implanted in the brain and produce
dopamine. The surgery has shown some success, but additional research is
necessary to fully determine the efficacy of the procedure.
In addition, the fields of genetics and biotechnology have uncovered some
pieces to the Parkinson's disease puzzle, but it likely will be years before
these technologies have an appreciable effect on current PD therapies.
Until a cure for Parkinson's disease is found, patients and physicians must
continue to pursue treatments that reduce the symptoms of the disease and
perhaps slow its progression. With the help of these therapies, patients now
are able to take control of PD and continue to live productive lives long after
the diagnosis.
-0- 11/16/95 /NOTE TO EDITORS: Physicians are
available for commentary./ /CONTACT: Sandra Perez, 212-880-5231, or Rona Gurin,
212-880-5252, both of Ogilvy Adams & Rinehart/
CO: American Parkinson's Disease Association ST: New Jersey IN: MTC SU:
