Long-term safety and sustained efficacy of extended-release pramipexole in early and advanced Parkinson's disease

BACKGROUND AND PURPOSE: To assess the long-term safety and efficacy of pramipexole as a once-daily (q.d.) extended-release oral formulation in early or advanced Parkinson's disease (PD). METHODS: In two double-blind (DB) studies of early PD and one of advanced PD, active-treatment arms received pramipexole immediate release (IR) or extended release (ER), with exposure lasting up to 33 weeks. In open-label (OL) extensions that followed immediately, subjects took ER q.d. for up to 80 weeks, with dosage adjustment permitted (range 0.375–4.5 mg q.d.). RESULTS: Of 590 subjects completing an early-PD DB study, 511 entered the early-PD OL extension; 408 completed it. Reported adverse events (AEs) with incidence ≥10.0% were somnolence (15.1%), peripheral edema (11.7%) and back pain (10.6%). Of 465 subjects completing the advanced-PD DB study, 391 entered the advanced-PD OL extension; 329 completed it. Reported AEs with incidence ≥10.0% were dyskinesia (27.4%) and somnolence (13.6%). Impulse control disorders were identified by semi-structured interview in 13 subjects (1.4% of 902). In exploratory analyses, adjusted mean Unified Parkinson's Disease Rating Scale (UPDRS) Parts II + III scores (excluding ex-placebo recipients) remained substantially improved from DB baseline scores prior to pramipexole introduction, at −6.6 and −6.3 points amongst ex-DB-ER and ex-DB-IR recipients after 113 weeks of pramipexole (33 DB plus 80 OL) in early PD, and −11.5 and −9.1 after up to 113 weeks (up to 33 DB plus 80 OL) in advanced PD. CONCLUSIONS: These results support the long-term safety and efficacy of pramipexole ER in early and advanced PD. AEs were typical for dopaminergic medications, and UPDRS scores suggested sustained symptomatic benefit.