An open-label, multicentre clinical trial to determine the levodopa dose-sparing capacity of pramipexole in patients with idiopathic Parkinson's disease

Ninety-three patients with idiopathic Parkinson's disease (PD) entered a 12 week open-label, baseline controlled, multicentre study. The study was des igned to determine the levodopa sparing effect of pramipexole as add-on tre atment in PD while maintaining an optimal clinical improvement in motor per formance. The overall reduction in adjusted levodopa dose was the primary e ndpoint. Unified Parkinson's Disease Rating Scale (UPDRS) subscores as well as motor fluctuations, frequency and severity of dyskinesia (assessed by p atient diaries) were secondary endpoints. Pramipexole permitted a median reduction of adjusted levodopa by 40% while maintaining or improving the UPDRS scores in 61 patients (per protocol [PP] analysis). The intent-to-treat (ITT) analysis (90 patients) similarly reve aled a median reduction of 40%. An anticipated short-term levodopa dose red uction as substantiated by 95% confidence interval calculations lies within a range of 35% to 50%. If unadjusted levodopa doses were considered, a med ian reduction of 42% (PP) or 43% (ITT) was achieved. 47% patients (ITT) had a levodopa dose reduction (adjusted) of more than 40% while maintaining or improving their level of efficacy, and 72.2% had a reduction of at least 2 0%. Motor fluctuations improved compared to baseline according to patient d iaries and UPDRS part IV. These findings suggest that pramipexole can markedly reduce the daily levod opa dosage without deterioration of motor response and support that this ne w selective D2/D3 receptor agonist also improves later levodopa-associated motor complications.