Drug Breakthroughs Offer Hope for Parkinson's Patients
Yet a cure remains elusive, researchers acknowledge
SUNDAY, July 4, 2004 (HealthDayNews) -- A drug approved in April by the U.S. Food and Drug Administration brings yet another source of relief to those who suffer from the debilitating malady known as Parkinson's disease.
The FDA granted approval to the drug Apokyn (apomorphine), made by Bertek Pharmaceuticals, which treats periods of immobility that affect some people with Parkinson's disease.
During these "off-period" episodes, medically known as "hypomobility," some people on standard anti-Parkinson's drugs can lose the ability to speak, rise from a chair, or walk. These episodes tend to occur as the drugs begin to wear off between dosing cycles.
The debilitating condition affects about 10 percent of the patients who take standard Parkinson's therapies.
Apokyn must be taken with another medication to counter its nasty side effects, which include severe nausea and vomiting, the FDA said. The drug's labeling also includes specific warnings about low blood pressure, fainting, hallucinations and excessive sleepiness.
Parkinson's disease involves the steady loss of brain cells that produce dopamine, a chemical messenger essential to proper motor function. As levels of dopamine decrease, chemical messages between brain cells misfire, triggering symptoms such as tremors, loss of balance, rigidity and other abnormalities.
An estimated 1 million to 1.5 million Americans have Parkinson's disease, a brain disorder that can cause tremors, difficulty walking and rigid muscles. In severe cases, patients can develop dementia and die from the disease. Parkinson's is largely a disease of the elderly, and is estimated to affect one in every 100 Americans over the age of 60.
Within the past year, the U.S. government has approved other drugs for Parkinson's treatment, among them Stalevo, which helps the "staying power of other Parkinson's medications like levodopa, from "wearing off" over time. Levodopa is the most widely used agent to treat Parkinson's, but its effects last for shorter and shorter periods over prolonged use. Where initially levodopa may have prevented the tremors and other symptoms of Parkinson's for as long as eight hours, a dose may eventually only last one or two hours, according to the manufacturer of Stalevo, Novartis Pharmaceuticals Corp.
A second ingredient in Stalevo, entacapone, blocks the enzymatic breakdown of levodopa, allowing the medication to control Parkinson's symptoms longer.
Meanwhile, a drug that may receive U.S. government approval later this year eases the symptoms of Parkinson's disease and may even slow progression of the degenerative condition, researchers have found.
There is currently no drug clinically proven to put the brakes on the steady destruction of cells within the brains of Parkinson's patients. The new drug, rasagiline, is the first medication to be tested under a new study protocol that looks at whether a medication can do more than just mask symptoms, the researchers said.
"Rasagiline works for helping signs and symptoms of Parkinson's -- and this study gives us hope that it does something beyond that," said study co-author Dr. Karl Kieburtz, a professor of neurology at the University of Rochester Medical Center.
The study appeared in the April 19 issue of Archives of Neurology.
New research into common factors in people with Parkinsons disease is pointing toward finding a way to cure it. One of those is finding the relationship between Parkinson's and the amount of iron and manganese a person has in his or her body.
Researchers suspect the minerals are somehow connected to the development of Parkinson's disease, but it's far from clear whether iron and manganese, found in a variety of healthy foods, actually make people ill.
"We don't know about cause and effect," said study author Karen Powers, a research scientist at the University of Washington. "We are not saying that we know what causes Parkinson's, and it's way too soon for us to make any recommendations about diet."
Researchers have suspected a link between iron and Parkinson's disease, but the new study is the first to look at the combined effects of both iron and manganese, Powers said.
Powers and her colleagues looked at two groups of people -- 250 who were newly diagnosed with Parkinson's disease and 388 healthy people. The researchers interviewed members of each group about their diets.
The findings appeared in the June 10 issue of Neurology.
Finally, the use of fetal cell transplantation -- long hoped to provide relief -- proved to be just the opposite, at least in initial trials.
Learn more about Parkinson's disease from the National Institute for Neurological Disorders and Stroke.