The purpose of this study is to evaluate blood level profiles of multiple oral doses of AP09004 vs. active control and to determine its safety and efficacy in Parkinson's patients.

• Subjects between the ages of 18 and 75 years of age inclusive;
• For early patients only: Subject with Parkinson's disease with a stable response to Levodopa (not suffering from "wearing off") and currently treated with IR-Carbidopa/Levodopa containing 300-500mg Levodopa per day up to 4 doses per day.
• For group 3 only: Subject with Parkinson's disease experiencing predictable motor fluctuations, end of dose "wearing off", defined by the patient's report of at least two episodes daily of a decline in function from peak benefit, with at least 2-3 hours OFF a day at the discretion of the PI (does not include early morning akinesia). Only patients with end of dose wearing off for at least 3 months will be included.
• For moderate patients only: patients who are currently treated with IR-Carbidopa/Levodopa containing 600-900mg Levodopa, in divided dose, per day.
• Subject has been stable at current CD/LD dose for at least 1 months
• Hoehn and Yahr stages I-III
• If subject is taking dopamine agonists, the dose has been stable for at least 1 month
• Other then Parkinson's disease, the subject is in satisfactory health, as assessed by physical examination, blood test (biochemistry and hematology). No abnormality on clinical examination and blood tests that in the opinion of the Physician responsible will compromise safety or interfere with study procedures.

Exclusion Criteria:

• Subjects who have participated in another clinical trial within the last 30 days;
• Subjects with atypical Parkinsonism
• Subject has significant history of cardiac, pulmonary, hepatic or renal disease or other condition or any major complication/illness which, in the opinion of the physician responsible, contraindicates his/her participation.
• Subject with symptomatic gastroparesis with frequent vomiting (at least once a week).
• Subjects with a history of clinically defined GERD, peptic ulcer or any gastrointestinal surgery other than appendectomy or herniotomy, or with any gastrointestinal disorder likely to influence drug absorption, or with any history of inflammatory bowel disease, irritable bowel syndrome, severe gastrointestinal narrowing, or frequent nausea or emesis, regardless of etiology.
• Prior gastro-intestinal surgery or current gastrointestinal conditions of clinical significance including ulcers, diarrhea, vomiting, bleeding, intestinal obstruction or inflammatory bowel disease, which, in the opinion of the physician responsible, contraindicates his/her participation.
• History of drug or alcohol abuse.
• Subject has a history of allergy to any component of the dosage form or any other allergy, which, in the opinion of the physician responsible, contraindicates his/her participation.
• Subjects suffering from psychological disorders that in the opinion of the physician responsible may interfere with full participation.