Isradipine fails to stop progression of Parkinson’s disease
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The dihydropyridine calcium-channel blocker isradipine did not slow the clinical progression of Parkinson’s disease, according to the results of a double-blind, placebo-controlled trial published in Annals of Internal Medicine.
“Several epidemiologic studies have demonstrated a reduced risk for Parkinson’s disease in persons receiving dihydropyridines compared with other antihypertensive agents,” Tanya Simuni, MD, FAAN, division head of the Parkinson’s Disease and Movement Disorders Center at Northwestern University Feinberg School of Medicine, wrote on behalf of the Parkinson Study Group Investigators. “Therefore, convergent data support isradipine’s potential to slow the progression of Parkinson’s disease.”
Researchers randomly assigned 336 patients (mean age, 62 years; 68% men; duration of disease, 0.9 year) in an approximate 1:1 ratio to 5 mg immediate-release isradipine or placebo twice a day for 36 months. None of the participants were taking dopaminergic medications.
According to researchers, the adjusted least-squares mean change in Unified Parkinson’s Disease Rating Scale part 1 to part 3 scores at the end of 36 months was 2.99 points (95% CI, 0.95-5.03) among patients who received isradipine vs. 3.26 points (95% CI, 1.25-5.26) among patients who received placebo. Simuni and colleagues wrote that the isradipine dose may have been too low to make a difference in the scores.
Researchers also reported that isradipine had no effect on the trial’s secondary outcomes: time to initiation and use of anti-Parkinson’s medications, time to onset of motor complications, change in nonmotor disability and quality of life measures. The most common adverse events among isradipine recipients were dizziness and edema.
“Compared with other recent studies of putative disease-modifying agents in early-stage Parkinson’s disease, [this trial] was unusual in extending follow-up to 3 years and assessing the primary outcome at 36 months, a time when most patients were receiving anti-Parkinson medications,” Simuni and colleagues wrote.
“Although we considered alternative study designs, including delayed start, prolonged washout, and a ‘simple, long-duration’ design, these would have required a substantially larger sample and have their own limitations. Finally, we do not believe that the choice of the primary outcome affected the study results because no secondary outcome measures showed a difference between groups,” they wrote.
Simuni and colleagues noted that further study may be warranted to evaluate the effectiveness of interventions to slow the progression of Parkinson’s disease, including inhibiting neurologically based caveolin-1 calcium channels or starting treatment at earlier prodromal stages. – by Janel Miller
Disclosures: Healio Primary Care could not confirm relevant financial disclosures at the time of publication.