Dihydropyridine calcium channel blockers and the progression of parkinsonism

Objective — A study was undertaken to test the association between dihydropyridine calcium channel blocker use and the time to important milestones of disease progression among patients with parkinsonism.

Methods — Data were obtained from Ontario's healthcare administrative databases. Within a cohort of hypertensive individuals older than 65 years who developed parkinsonism, the researchers examined the effect of the length of exposure to less brain-penetrant dihydropyridines (amlodipine) and more brain-penetrant dihydropyridines (e.g., nifedipine, felodipine) on parkinsonism milestones as measured by time to requiring drug treatment for parkinsonism, nursing home admission, and death.

Results — Among 4,733 hypertensive individuals with parkinsonism, longer treatment with any dihydropyridine was associated with a decreased risk of each of the 3 outcomes. There was no difference, however, between amlodipine (adjusted hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.42–0.50 for initiation of drug treatment; HR, 0.68; 95% CI, 0.63–0.73 for application for nursing home admission; and HR, 0.75; 95% CI, 0.70–0.80 for death) and nonamlodipine dihydropyridines (adjusted HRs [95% CIs], 0.45 [0.39–0.53], 0.74 [0.67–0.81], and 0.74 [0.64–0.85] for the 3 milestones, respectively).

Interpretation — The researchers found no specific beneficial effect of treatment with brain-penetrant dihydropyridines on delaying parkinsonism progression milestones. Dihydropyridine calcium channel blockers are unlikely to have a clinically significant effect on the course of parkinsonism, particularly Parkinson disease, in the doses used to treat hypertension.