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WEDNESDAY, January 23, 2019 (HealthDay News) – A new clinical trial has concluded that the most potent drug available for Parkinson's disease, levodopa, treats its symptoms but does nothing to reduce or increase its causes. -Jamentes, which remain mysterious.
Doctors are often slow to prescribe levodopa or L-dopa to patients with Parkinson's disease, lest the drug has toxic effects that produce jerky movements of the body over time.
However, patients started taking L-dopa almost a year earlier than a second group did not develop very different rates of involuntary movements, according to the results of the new test.
"The ongoing study reinforces our confidence that levodopa is safe even at the onset of Parkinson's disease and that patients should not be afraid of it," said Dr. Michael Okun. He is the National Medical Director of the Parkinson's Foundation and Chair of the Neurology Council of the University of Florida at Gainesville.
There is disappointment here too. Although levodopa is not toxic, it does not appear to provide protection against the progression of Parkinson's disease in the brain, said Dr. Susan Bressman, co-director of Mount Sinai Parkinson and the Movement Disorders Center in New York. .
"In the end, they could not show neuroprotection," said Bressman. "Using this very normal dose that we normally use, they could not show that it slowed the progression of the disease."
Parkinson's disease is a progressive disorder of the nervous system. One of its features is the loss of neurons that produce a chemical called dopamine in the brain. Low levels of dopamine affect a person's movement control, causing tremors, stiff muscles and sluggishness.
Developed more than 50 years ago, L-dopa alleviates these muscular and motor symptoms. The brain synthesizes levodopa into dopamine and then uses the neurotransmitter wisely.
"Levodopa remains the most important and effective treatment for Parkinson's disease and its introduction has undoubtedly improved morbidity, mortality, and quality of life," said Okun, who was not part of the team. 39; test.
But side effects in some patients are fears that the drug may have a toxic effect on the brain, noted the researchers.
A clinical trial 14 years ago to clarify the issue has only blurred the trail, Bressman said.
The previous trial had shown that people taking L-dopa had shown improvement even after discontinuing it, which gave hope that it could somehow slow down the progression of Parkinson's disease.
However, brain tests of these patients have shown that levodopa causes potentially harmful modifications of dopamine receptors in the brain, Bressman said.
"We could not really prove one way or another if it's good or bad for the brain," Bressman said. "But the end result – people need it.We have no better medicine.It is the most powerful drug against the symptoms, so you have to use it, but you do not have to." Do not use a high dose. "
The new clinical trial, led by Dr. Rob de Bie of the University of Amsterdam, hoped to clarify the results of the older study.
In the Netherlands, a group of 445 patients with Parkinson's disease were randomized to start levodopa treatment immediately or wait 40 weeks before starting the drug.
"The theory is that if you get those 40 extra weeks of exposure to levodopa and its neuroprotective effect, the previous group will be in a better place and the late group will never catch up," Bressman said. "They will always be a little worse because the first group has benefited more from this neuroprotective effect."
Dutch researchers found that both groups found themselves in the same place at the 80th week of the trial, with essentially the same rate of progression of the disease. The drug did not provide any additional protection to those in the previous group.
At the same time, neither group experienced higher rates of jerky movements or motor response fluctuations related to levodopa, alleviating concerns about toxic effects.
"Basically, this confirms what we are doing now," said Bressman, co-author of an editorial accompanying the study. Both were published in the January 24 issue of New England Journal of Medicine.
"Most people do not start levodopa at first diagnosis because they have virtually no symptoms because they do not need it, we do not think the drug protects the brain, we do not start it all. This will not change what they will look like in 10 years, "she said.
"But as soon as they start to need it, we start it, we use it, and we are wise in using it," Bressman said.
Hopes for a drug that will directly treat or perhaps even cure Parkinson's disease now rest on research conducted on the suspected causes of the disease, she said.
Experts now believe that Parkinson's is a group of related diseases, each subtype being triggered by a different cause, Bressman said.
Drugs are being developed to target genes involved in Parkinson's disease in some patients. Future drugs could target inflammation in the brain or other potential causes.
"Ultimately, between genetics and other biomarkers found in cerebrospinal fluid or in the blood, we will be able to better group patients and better understand the mechanisms of the disease," said Bressman.
More information
The Michael J. Fox Foundation for Parkinson's Research says more about the myths surrounding levodopa.
SOURCES: Michael Okun, M.D., National Medical Director, Parkinson Foundation, and President, Neurology, and Co-Director, Movement Disorders Center, University of Florida, Gainesville; Susan Bressman, MD, co-director, Mount Sinai Parkinson and Movement Disorders Center, New York; New England Journal of MedicineJanuary 23, 2019
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