Bedtime cabergoline in Parkinson's disease patients with excessive daytime sleepiness induced by dopamine agonists

Excessive daytime somnolence is a common adverse effect of dopamine-agonist treatment of Parkinson's disease (PD). Many factors, such as age and sleep disturbances, could be involved in the pathogenesis of this phenomenon. However, pharmacokinetic factors have never been considered. In this open, prospective, pilot study, nine consecutive non-demented PD patients in early disease stages on monotherapy treatment with dopamine agonists and with no significant sleep problems, were enrolled. They were selected based on the presence of excessive daytime sleepiness induced by the dopaminergic treatment. A fast switch-over from the dopamine agonist currently used to a single equivalent dose of cabergoline, a long-acting dopamine agonist, administered at bedtime was performed. All patients were evaluated by means of UPDRS and Epworth Sleepiness Scale (ESS). A significant 70% reduction of daytime sleepiness was observed during the 3-month study compared with baseline. Data from this study suggest that both pharmacodynamic and pharmacokinetic mechanisms are involved in the pathophysiology of dopamine agonist-induced sleepiness.