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Studies Offer Some Encouraging News About Parkinson's Drugs

One treatment may help combat dementia suffered by some patients

WEDNESDAY, Dec. 8, 2004 (HealthDayNews) -- Two separate studies offer some good news about two drugs for the treatment of Parkinson's disease.

One found that rivastigmine, a drug now marketed to treat Alzheimer's disease, can slow the dementia experienced by many Parkinson's patients -- the first time a medication has been shown to have that benefit.

The other found that levodopa, widely used to control the trembling and other physical symptoms of Parkinson's, does not accelerate damage to nerve cells, as some physicians have feared.

Both studies appear in the Dec. 9 issue of the New England Journal of Medicine.

"These [dementia] patients have not had any treatment at all available to them," said Dr. Roger Lane, head of dementia research at Novartis Pharmaceuticals, which markets rivastigmine as Exelon. "We are very proud to have been able to show in a well-controlled study that a medication can help these patients and can bring some benefits for their cognitive and behavioral functioning problems."

Lane acknowledged the drug has its limitations. "If you are looking for a cure, this is not a cure," he said. "But it is an advance."

Novartis has begun discussions with the U. S. Food and Drug Administration about getting approval for use of the drug in the 40 or more percent of Parkinson's patients who develop dementia, Lane said.

However, in an accompanying editorial in the journal, Dr. Daniel Z. Press, an instructor in neurology at Beth Israel Deaconess Medical Center in Boston, said the results "are not as impressive as one would have hoped." But, he added, the finding does warrant use of the drug for some Parkinson's patients even before FDA approval.

Patients who might benefit from the drug are those whose dementia "is severe enough to be impacting their daily function," Press said. "I would try it and then judge whether the response is good enough to warrant continuing."

All the patients in the study had Parkinson's-related dementia. Those given rivastigmine for 24 weeks had an average improvement of 2.1 points on a standard 70-point scale of mental function. Those given a placebo averaged a 0.0-point loss. The results were "similar to those reported in trials of rivastigmine for Alzheimer's disease," the researchers wrote.

The levodopa trial included 361 newly diagnosed Parkinson's patients at 38 centers in the United States and Canada. They were divided into four groups. Three were given different doses of levodopa, while the fourth was given a placebo.

Patients getting the highest doses of levodopa had significantly more side effects, such as headache and nausea, than those getting the lower doses. But the severity of the disease increased much more in the patients who got a placebo compared to those who got any dosage of levodopa.

"Although there is still uncertainty about how to interpret the study and further investigation will be needed to prove levodopa's valuable beyond reasonable doubt, we found that levodopa did not accelerate the pace of Parkinson's disease," study leader Dr. Stanley Fahn, a professor of neurology at Columbia University Medical Center, said in a statement. "Now patients can feel more secure about the drug and may wish to start it sooner rather than later."

But levodopa does not stop the progressive brain damage caused by Parkinson's disease, the researchers noted. A new study is being planned to look at the nerve degeneration caused by the condition.

More information

The National Institute of Neurological Disorders and Stroke discusses the basics of Parkinson's disease.

SOURCES: Roger Lane, M.D., head, dementia research, Novartis Pharmaceuticals, East Hanover, N.J.: Daniel Press, M.D., instructor, neurology, Beth Israel Deaconess Medical Center, Boston; Dec. 9, 2004, New England Journal of Medicine
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