Safety and Efficacy Study of SYN115 in Parkinson's Patients Using Levodopa to Treat End of Dose Wearing Off

Inclusion Criteria:

- Meet Parkinson's Disease (PD) diagnosis consistent with UK PD diagnostic criteria

- Meet Hoehn and Yahr PD stage

- Good response to levodopa

- Stable regimen of anti-parkinson medications

- Are able to complete a Parkinson's disease diary

- If of childbearing potential(male and female), use an acceptable method of birth
control

- Able and willing to sign an IRB/IEC approved informed consent

- Able and willing to understand study requirements, follow study instructions, attend
all visits and undergo all planned tests.

Exclusion Criteria:

- Secondary or atypical Parkinson's

- Neurosurgical intervention for Parkinson's disease

- Treatment with apomorphine

- Treatment with anti-psychotic drugs

- Other abnormal findings on physical or neuro exam or history that in the opinion of
the investigator would make subject unsuitable for the study or prejudice safety and
efficacy evaluation

- MMSE less than 26

- Subjects with untreated or uncontrolled current episode of major depression

- Receipt of any anti-psychotic drugs greater than 1 month in the past 5 years or any
exposure in past year (except for quetiapine at doses <100mg per day)

- Women pregnant or lactating

- History of hepatitis, cholangitis

- Untreated or uncontrolled hypothyroidism or hyperthyroidism

- Drops in blood pressure requiring medication to maintain blood pressure

- Any clinically significant out of range laboratory evaluations

- Known sensitivity to the study medication or its components

- Suicide ideation or type 4 or type 5 on the Columbia suicide severity rating scale

- Finding of malignant melanoma on full body skin exam

- Impulse disorder conditions