"This is really one of those moments in medicine when we can say that we are looking at the possibility of fundamentally changing the way we treat a major disease," Dr. Warren Olanow, a leading Parkinson's expert and professor of neuroscience at Mount Sinai School of Medicine in New York City, said at a news briefing earlier this week. Currently approved treatment delivers the drug levodopa through a pill and intestinal absorption, but the level of dopamine that the brain needs (and is missing in Parkinson's disease) fluctuates during levodopa treatment in what is called the peak-and-trough effect. The result is eventual loss of motor control.

Rotigotine, however, is delivered continuously via a skin patch, which allows the level of dopamine in the blood and brain to remain constant.

"Motor complications are common in Parkinson's disease, in as many as 80 percent of patients treated with levodopa for five years or more," Olanow told United Press International. "They can be a major source of disability for some patients. Patch rotigotine is associated with a constant plasma level and accordingly should be associated with a marked reduction in motor complications in comparison to levodopa."

Results of the two new studies were presented Sept. 18 in Athens at the annual meeting of the European Federation of Neurological Societies.

In the first, investigators added rotigotine to the treatment of patients with advanced-stage Parkinson's who already were being given levodopa. The study randomly assigned 341 patients to two different strengths of rotigotine or placebo.

Treatment groups involved 113 subjects receiving a 40-centimeter rotigotine patch delivering 8 mg per day; 109 subjects receiving a 60-centimeter patch delivering 12 mg per day, and 119 subjects receiving a placebo.

Patients given the highest dosage of rotigotine experienced almost three fewer hours per day of motor complications, and 99 percent chose to continue the patch at the end of the trial.

"The addition of rotigotine did what we had hoped it would do: cut significantly the adverse motor effects of levodopa, while not interfering with its efficacy," said Dr. Peter Le Witt, the lead investigator and professor of neurology and psychiatry at Wayne State University School of Medicine in Detroit.

In another trial, rotigotine was administered without levodopa to 273 early-stage patients, of which 177 were assigned to receive the drug, and 96 a placebo, for six months.

The rotigotine subjects started on a 10-centimeter patch delivering 2 mg per day. Then the researchers increased the patch size by 10 centimeters each week over three weeks, to a maximum patch size of 30 centimeters delivering 6 mg per day.

Patients in the rotigotine group showed a significant average improvement on their standard Parkinson's scores, compared to the placebo group, whose scores worsened significantly. Of the patients who completed the study, 97 percent continued on rotigotine.

"These studies indicate two crucial advantages in this potential new treatment," Olanow said. "It has anti-Parkinson effects when used as initial therapy for Parkinson's, and therefore will help new patients avoid treatment-related problems. For advanced-stage patients, there are significant anti-Parkinson effects when rotigotine is used as an addition to levodopa. This could change many lives."

Representatives of Schwarz Pharma, the developer of rotigotine, announced at the meeting they expect a decision from the FDA sometime next year.