Sublingual apomorphine in the treatment of Parkinson's disease

Advanced Parkinson´s disease (PD) is often complicated by fluctuations of disability depending on plasma levels of levodopa. For most patients OFF phases with worsening of tremor and immobility, but also pain, depression, autonomic symptoms are troublesome. While adjustments of levodopa administrations can relief such fluctuations for some time, "on demand" therapies become more and more important. These "on demand" therapies should provide fast and efficacious relief. During the past years, new options for on demand therapies in PD-associated OFF episodes have been developed, including new formulations of levodopa and apomorphine to provide fast and readily accessible on demand treatment. In this narrative review, the challenges of the treatment of PD-associated fluctuations and OFF states are addressed, with a special focus on sublingual apomorphine (SL-APO) including the results from recent clinical trials.