Continuous dopaminergic delivery in Parkinson’s disease

Motor fluctuations and dyskinesias occur in the majority of patients with Parkinson’s disease (PD) and are likely to result from changes in dopamine production, storage and release, occurring as consequences of the nigrostriatal degenerative process. All studies comparing levodopa versus dopamine agonist early therapy indicate that initiation with agonists is associated with a reduced risk of motor complications —in particular, dyskinesias— possibly because agonists’ longer half-lives provide continuous dopaminergic delivery. In advanced PD patients, switching from a pulsatile to continuous dopaminergic delivery may widen patients’ therapeutic window. Currently, this can be accomplished only with subcutaneous apomorphine or duodenal levodopa infusions. Apomorphine is a highly soluble agonist whose effect is similar to dopamine. Conversely, replacing whole oral therapy with levodopa infusion bypasses gastric emptying and avoids peaks and troughs in plasma by releasing levodopa in the duodenum/jejunum.