Drug Shows Promise Against Parkinson's

Rasagiline first to show evidence of slowing brain deterioration

MONDAY, April 19, 2004 (HealthDayNews) -- A drug expected to 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 appears in the April 19 issue of Archives of Neurology.

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. Parkinson's is progressive and has no cure, although certain drugs can ease its symptoms. The National Parkinson's Foundation estimates that 1.5 million Americans are affected with the disease.

In their study, conducted in 32 clinics across North America, Kieburtz and his colleagues tested rasagiline on more than 400 patients diagnosed with early-stage Parkinson's. "This is a very mild stage, where they have enough symptoms to make a diagnosis but they don't have any functional impairment, so they're not on any medication yet," he explained.

In typical clinical drug trials, researchers give one group of subjects the medication under study while another group receives a placebo. The participants are then tracked for a period of time while changes in their symptoms are compared, to determine the drug's effectiveness.

In this case, however, the researchers fully expected that rasagiline would quell symptoms, since is a close chemical relative of an existing Parkinson's drug, selegiline. Instead, they wanted to go further, examining whether it might slow disease progression in the brain.

To do so, they designed a "delayed-start" study, where half of the participants started the drug six months after the other half.

"What you would expect is that if the drug is having no effect on disease progression, adding the pill later should have the same effect as having the pill earlier," Kieburtz explained.

That wasn't the case, however.

While all of the patients in the study experienced "appreciable" reductions in shaking, stiffness and other Parkinson's symptoms, "they never got as good as the people who started it earlier," Kieburtz said. This suggests the group who received the drug six months earlier had gotten a jump on slowing disease progression, he says.

Kieburtz stressed that existing drugs such as selegiline might produce similar results if subjected to the same kind of testing. In fact, his group is now seeking funding for a delayed-start study focused on levodopa, the medication most often used in the fight against Parkinson's.

Overall, rasagiline appeared to match other drugs when it came to reducing symptoms, the researchers report, while producing fewer side effects. According to Kieburtz, the drug is currently winding its way through the U.S. Food and Drug Administration approvals process and "may enter the market this year."

Some experts remain unconvinced that rasagiline slows disease progression, however.

"Would I use the drug in my patients? Yes. Would I put every one of my patients on the drug because it may slow the progression? No -- I'm not sure I believe that yet," said Dr. Abraham Lieberman, a professor of neurology at the University of Miami and medical director of the National Parkinson's Foundation.

Lieberman believes more study needs to be done to prove that rasagiline -- or any drug -- has an effect on the course of Parkinson's disease. Proponents for other drugs have put forth similar theories in the past, he noted, with disappointing results.

"This drug is welcome, it'll be used, it'll find a niche," he said. But before he would prescribe it to all his patients, "I'd have to have better evidence."

Kieburtz agreed that much more study is needed. "I think this is a very useful drug," he said. "It's taken once a day, it has modest but appreciable benefits. But it's not a silver bullet."

More information

Learn about the disease from the National Institute for Neurological Disorders and Stroke, while the National Parkinson Foundation discusses drugs.

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