Constant dopaminergic stimulation by transdermal delivery of dopaminergic drugs: a new treatment paradigm in Parkinson's disease.

Current dopaminergic therapies for the treatment of Parkinson's disease are associated with the development of long-term motor complications. Abnormal pulsatile stimulation of dopamine receptors is thought to underlie the development of motor complications. There is thus a need for therapies that mimic the normal physiological state more closely by resulting in constant dopaminergic stimulation (CDS). Several studies support the hypothesis that CDS can reverse levodopa-induced motor complications. Other potential benefits of CDS include alleviating nocturnal disturbances, minimizing daytime sleepiness, avoiding priming for motor fluctuations and dyskinesia, preventing the development of gastrointestinal dysfunction and reducing the risk of developing psychosis or behavioural disturbances. Continuous infusion of dopaminergic therapies is impractical for the routine treatment of large numbers of patients. Although catechol-O-methyltransferase inhibitors or sustained-release preparations of levodopa may be beneficial, they do not entirely eliminate pulsatile stimulation of dopamine receptors. A new dopamine agonist (rotigotine), delivered over 24 h by a once-daily transdermal patch, has been investigated in several clinical trials. Continuous delivery of rotigotine has been shown to provide 'true' CDS in animal models. The potential of true CDS therapy to prevent or reduce long-term motor and non-motor complications requires investigation in appropriately designed clinical trials.