A study of a blood pressure drug does not show any benefit for people with Parkinson's disease, according to findings released today that will be presented at the American Academy of Neurology's 71st Annual Meeting in Philadelphia, PA, May 4 to 10, 2019.

The drug isradipine had shown promise in small, early studies and hopes were high that this could be the first drug to slow the progression of the disease.

"Unfortunately, the people who were taking isradipine did not have any difference in their Parkinson's symptoms over the 3 years of the study compared to the people who took a placebo," said study author Tanya Simuni, MD, of Northwestern University Feinberg School of Medicine in Chicago, IL, and a member of the American Academy of Neurology.

The phase 3 study involved 336 people with early Parkinson's disease at 54 sites in the United States and Canada as part of the Parkinson Study Group. Half of the participants received 10 milligrams daily of isradipine for 3 years, while the other half received a placebo.

The drug had shown promise in animal studies, and a phase 2 study in humans did not show any safety concerns. Researchers became interested in the drug when the observation was made that use of the drug for high blood pressure was associated with a lower risk of developing Parkinson's disease.

"Of course, this is disappointing news for everyone with Parkinson's disease and their families, as well as the research community," Simuni said. "However, negative results are important because they provide a clear answer, especially for the drug that is commercially available. We will all continue to work to find a treatment that can slow down or even cure this disease."