Efficacy, safety, and tolerability of overnight switching from immediate‐ to once daily extended‐release pramipexole in early Parkinson's disease

Abstract

The aim of this article is to test the feasibility, in early Parkinson's disease (PD), of an overnight switch from immediate-release (IR) pramipexole to a new once-daily extended-release (ER) formulation. Nonfluctuating patients on pramipexole IR three-times daily, alone or with levodopa, for early PD were randomly switched overnight to double-blind IR three-times daily (N = 52) or ER once-daily (N = 104) at initially unchanged daily dosage. Successful switching (defined as no worsening >15% of baseline UPDRS II+III score and no drug-related adverse event withdrawal) was assessed at 9 weeks, after optional dosage adjustments (primary endpoint), and at 4 weeks, before adjustment. Other secondary endpoints included adjusted mean changes from baseline in UPDRS scores and proportion of responders based on Clinical or Patient Global Impression (CGI/PGI). Absolute difference between percentage of successful switch to ER versus IR was tested for ER noninferiority, defined as a 95% confidence-interval lower bound not exceeding -15%. At 9 weeks, 84.5% of the ER group had been successfully switched, versus 94.2% for IR. Noninferiority was not demonstrated, with a difference of -9.76% (95% CI: [-18.81%, +1.66%]). At 4 weeks, 81.6% of the ER group had been successfully switched, versus 92.3% for IR, a difference of -10.75% (95% CI: [-20.51%, +1.48%]). UPDRS changes and CGI/PGI analyses showed no differences between the groups. Both formulations were safe and well tolerated. Pramipexole ER was not equivalent to IR, but the difference was marginal. The fact that >80% of the patients successfully switched overnight at unchanged dosage shows that this practice was feasible in most patients.