New Parkinson's Drug Draws Mixed Reviews

Sept. 24 -- WEDNESDAY, Sept. 23 (HealthDay News) -- A study to see whether a new drug can stop the progression of Parkinson's disease has produced results that have drawn sharply differing reactions from neurologists.

The drug, rasagiline (Azilect), was approved in 2006 by the U.S. Food and Drug Administration on the basis of studies showing that it reduced Parkinson's symptoms such as trembling and slowed motion. The new study, reported in the Sept. 24 issue of the New England Journal of Medicine, was designed to determine whether the drug also acts on the underlying nerve deterioration that causes the disease.

"In our heart, what we are hoping for is neuroprotection," said study author Dr. C. Warren Olanow, a professor of neurology and neuroscience at Mount Sinai School of Medicine, in New York City.

To distinguish the effect on symptoms from the hoped-for effect on the underlying disease, "we used a totally new study design, to see if it is disease-modifying," Olanow explained.

The study enlisted 1,176 people with previously untreated Parkinson's disease who were seen at medical centers around the world. At the start, half took daily doses of either 1 milligram or 2 milligrams of rasagiline for 36 weeks, while the other half took a placebo. After that, all the participants took either 1 milligram or 2 milligrams of rasagiline for another 36 weeks.

A complex system to measure the treatment effects showed an apparent improvement in the participants who took the 1-milligram doses but not in those taking the 2-milligram doses.

"It did something to affect the course of the disease," Olanow said. "We don't know why, but we are entitled to speculate."

His speculation is based on a detailed study of the 25 percent of participants who showed the greatest benefit. "What I think is right is that the higher dose had a greater effect on symptoms than the lower dose, so that masked our ability to detect its effect on disease progression," Olanow said. "We thought that this floor effect was why we couldn't see a difference."