The long-term safety and efficacy of pramipexole in advanced Parkinson's disease.

Objective: To assess the long-term safety and efficacy of pramipexole in advanced Parkinson's disease over a four year time period.Methods: This study is an open-label extension trial of pramipexole for Parkinson's disease open to patients completing a double-blind placebo controlled safety and efficacy trial of this drug. Three hundred and six patients entered the trial. These patients had moderate to severe PD (stage II-IV Hoehn and Yahr during off time) and were experiencing motor fluctuations. Patients were titrated over a six week period and then entered a maintenance phase which lasted up to 50 months. Patients were evaluated every 3 months using the Unified Parkinson's Disease Rating Scale (UPDRS II, III and IV) and modified Schwab and England scale (S/E).Results: Sixty-four percent (197) of the 306 patients who entered this study completed it. Patients showed steady improvement over the 6 week ascending dose interval when pramipexole was reintroduced into the trial as the open-label study medication. Over the duration of the trial patients slowly returned to their baseline levels. This was true for all measures evaluated except for the UPDRS part IV. On UPDRS part IV patients remained below their baseline score which indicated an improvement for the duration of the study. Patterns similar to the overall scores were seen when the individual components of the UPDRS scale part II for "on" and "off" periods and part III were evaluated. However tremor during "on" periods showed improvement over baseline for the duration of the trial. The most common adverse events secondary to pramipexole occurring in greater than 10% of patients included dyskinesias, asymptomatic orthostatic hypotension, dizziness, insomnia, and hallucinations.Conclusion: Pramipexole was well tolerated for up to 4 years. Pramipexole treatment appeared to show continued efficacy in the treatment of Parkinson's disease for 3 years in this open-label descriptive study. After 3 years there was a gradual return to baseline motor states perhaps suggesting progression of Parkinson's disease.