Tolerability of isradipine in early Parkinson's disease: a pilot dose escalation study.

Recent data suggests that isradipine, a dihydropyridine calcium channel blocker, is neuroprotective in preclinical models of parkinsonism. Isradipine has not been systematically studied in patients with Parkinson's disease (PD). The aim of this study was to evaluate safety and tolerability of isradipine controlled release (CR) in patients with early PD. Qualified subjects (n = 31) received isradipine CR, titrated from 5 to 20 mg daily dose over 8 weeks as tolerated. Eighty-one percent of subjects completed the study. Tolerability of isradipine CR was dose dependent: 94% for 5 mg dose; 87% for 10 mg; 68% for 15 mg; and 52% for 20 mg. Isradipine had no significant effect on blood pressure or PD motor disability. The two most common reasons for dose reduction were leg edema (7) and dizziness (3). There was no difference in isradipine tolerability between subjects with and without dopaminergic treatment, or with and without hypertension.