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Isradipine Study Results Disappointing

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The prevalence of Parkinson’s disease (PD) is expected to double in the next 20 years. To date, there are no proven strategies for slowing the progression of PD. A calcium channel blocker medication used to treat hypertension called, Isradipine, has been shown to be neuroprotective in animal models of PD. Several studies of people also indicated the possibility that taking Isradipine may reduce the risk for PD.

A study published in Annals of Internal Medicine, “Isradipine Versus Placebo in Early Parkinson Disease: A Randomized Trial” (Parkinson Study Group, 2020), sought to determine if treatment with Isradipine was effective in slowing the progression early-stage PD (within three years of diagnosis). The study lead was Tanya Simuni, MD, of the Parkinson’s Foundation Center of Excellence at Northwestern University Feinberg School of Medicine. 

isradipine pill

This double-blind, placebo-controlled study recruited participants from 57 Parkinson Study Group sites from the U.S. and Canada. All 336 participants (68% men, 32% women) had been diagnosed with early PD, were 30 years of age or older, had minimal disability and none were taking any dopamine medication.

For 36 months, approximately half of the participants were given 5mg of immediate release Isradipine twice daily, and 166 were given a placebo, also twice daily. Motor function, cognitive function, global measures of disability, functional status and quality of life were measured at baseline, and again at the study conclusion.


While the study research was sound, unfortunately the data revealed that Isradipine did not slow PD progression. Unwanted side effects occurred in less than 5% of the participants, with dizziness and edema (water retention) being the most common.

What Does This Mean?

Compared to taking a placebo, taking 5mg of Isradipine twice daily over the course of 36 months confers no protective benefit in slowing the progression of PD. In other words, the Isradipine did not work as hoped.

Important Recommendation

It is recommended that those who decided to take Isradipine ― who were not part of the study ― discuss the next steps with their doctors. Long-term use of anti-hypertensives in Parkinson’s can sometimes lead to passing out especially if not monitored and managed. This is because in Parkinson disease, both progression and dopamine medications can lower blood pressure. Long-term, many patients cut down anti-hypertensive drug dosages and sometimes even discontinue these medications.

Learn More

Learn more about Parkinson’s and medications in the following Parkinson’s Foundation resources or by calling our free Helpline at 1-800-4PD-INFO (473-4636):

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