The impact of extended release dopamine agonists on prescribing patterns for therapy of early Parkinson's disease: an observational study

Background: Dopamine agonists (DA) are the first-choice drug for treatment of the early stage of Parkinson's disease (PD) in subjects younger than 70 years. Recently, a number of third generation DA have been marketed, including transdermal patch of rotigotine and extended release oral formulation of ropinirole and pramipexole. We investigated the impact of third generation DA on management of the early stage of PD in an outpatient service for Movement Disorders in Italy. Methods: Two 12-month observation periods were selected (January - December, 2007, and January - December, 2011) as representative for prescription of immediate and extended release formulations of DA respectively. Within each period, PD patients were divided into subgroups according to age (<65 years; 65-75 years; >75 years) or functional requirement (high; moderate; low). For each period, the number of subjects receiving monotherapy with DA, monotherapy with levodopa (LD), or combined DA/LD therapy and the relative doses were calculated. The severity of parkinsonian motor symptoms was calculated by means of the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) score. The frequency and severity of side-effects leading to discontinuation or reduction of DA drugs at each time point were also calculated. Results: We found a significant reduction of daily LD dose (both as mono-and combined therapy) between the second and the first observation period. There was also a significant increase of monotherapy with DA and corresponding reduction of monotherapy with LD in patients aged 65-75 years, as well as in PD patients with moderate functional requirements. A significant reduction of frequency of side-effects was measured with extended release DA as compared to immediate release formulations. There were no significant differences of the UPDRS-III scores between the 2 observation periods in any subgroup. Conclusions: Our results suggest that extended release DA might optimize therapeutic management of the early stages of PD even in patients older than 70 years of age.