Emerging drugs for Parkinson's disease.

Parkinson's disease (PD) afflicts millions of people worldwide. There are numerous drugs available for PD; however, levodopa remains the gold standard of pharmacotherapy to which all other therapies are compared. Levodopa is quite effective for many motor symptoms (bradykinesia, tremor, rigidity) of PD; however, non-levodopa-responsive motor symptoms (postural instability) and nonmotor symptoms are frequently the most troublesome in middle and later stages of disease. Although motor symptoms remain an important focus for emerging drugs, current research is largely geared to identify and develop disease-slowing therapies. Another important area of focus has become treatment of the nonmotor symptoms of PD (especially depression and dementia). This review discusses emerging drugs in the management of the motor and nonmotor symptoms of PD and drugs under study as disease-slowing/neuroprotective agents.