Self-Reported Adherence after Overnight Switching from Immediate- to Extended-Release Pramipexole in Parkinson’s Disease

Background: Drug adherence decreased in patients with Parkinson' s disease (PD) because of tak- ing many different types of drugs. We evaluated drug adherence after switching from imme- diate-release (IR) to once-daily extended-release (ER) pramipexole (PPX) in PD. Methods: This study included 35 PD patients (20 men, 15 women); 10 were taking oral PPX alone, and 25 were also using another anti-PD drug. PPX-IR was switched overnight to PPX-ER without gradual taper- ing. One month after switching, improvement in timing adherence and reduction in medication burden were evaluated by a questionnaire using a visual analog scale (VAS) (0: No change; 10: Better). Motor function was assessed using part III of the Unified Parkinson's Disease Rating Scale (UPDRS). Results: The VAS score for improvement in timing adherence was 8.1 ± 0.5 (mean ± standard error), and that for reduction in medication burden was 7.3 ± 0.6. There was a significant negative correlation (ρ = −0.43, p = 0.01) between the VAS score and number of types of medica- tions. The UPDRS part III score improved significantly after switching (p < 0.01). Only one patient discontinued PPX-ER after switching. Conclusion: Switching from PPX-IR to once-daily PPX-ER is safe and improves motor function in patients by improving timing adherence and reducing medi- cation burden.