Levodopa, whether as monotherapy or in combination with DOPA decarboxylase, COMT and MAO-B inhibitors, is the gold standard for the treatment of motor symptoms in patients with Parkinson’s disease (PD). Cardinal motor symptoms such as rigidity, tremor and bradykinesia are reasonably well controlled by levodopa, but non-responsive motor symptoms do exist, such as postural stability, and motor complications are common in patients with moderate or advanced PD receiving levodopa. In addition, non-motor symptoms, that become increasing debilitating as the disease progress, are generally not susceptible to levodopa therapy.

As a result, research continues to focus on identifying targets for the development of novel therapeutic strategies for the control of both motor and non-motor symptoms. Furthermore, current strategies are aimed at preventing the onset of disease, and slowing or halting disease progression, rather than simply alleviating symptoms.