Patient description: The patient is a 55-year-old man who was recently diagnosed with Parkinson's disease. He is complaining of slowness of movement and tremors. His disease is ranked as mild, Hoehn-Yahr Stage I. His past medical history is significant for hypertension and hypercholesterolemia. He lives with his wife. They have three children. He used to be active with gardening before his diagnosis. He complains of shaking and slow movement. He had difficulty entering through a door, as he was frozen and needed guidance to step in. His handwriting is getting smaller. He is offered Levodopa and Trihexyphenidyl. He is an alert and cooperative man who does not have any signs of dementia. He does not smoke or use any illicit drugs.

Clinical trial eligibility criteria: eligible ages (years): 20.0-999.0,  Parkinson's Disease Men and women aged 20 years or older at the time of giving informed consent Patients who have idiopathic Parkinson's disease Patients who have been on a stable regimen of levodopa (at least three times daily) plus at least one other antiparkinsonian agent being administered or more frequently for at least 30 days before the preliminary evaluation and who have predictable end-of-dose wearing-off Patients who meet both of the following on the Modified Hoehn and Yahr Scale during the preliminary evaluation and on the day before starting study drug (Day -1) Stage IV or V while in the OFF state Stage II to III while in the ON state Patients who have experienced a 30% or more improvement in UPDRS Part 3 score when tested for responsiveness to levodopa during the baseline period Patients who have at least one wearing-off episode per day and a daily average OFF time of at least two hours two days before starting study drug (Day -2) and on Day -1 Patients who can understand the OFF state or have a family member who can understand it Patients who have given written informed consent. (Alternatively, the patient's legally acceptable representative may give written consent following the patient's oral consent, if his/her condition makes handwriting difficult.)  Patients with an illness of the cardiac, hematologic, hepatic, renal, pancreatic, metabolic, respiratory, gastrointestinal, endocrinologic, or neurologic system or a tumor that is clinically significant for their participation in the study Patients with orthostatic hypotension Patients with a history of drug allergies Patients with a history of intolerance to morphine or its derivatives, sulfur, sulfur-containing pharmaceutical products, or sulfite Patients with a history of malignant syndrome Patients with a diagnosis of cancer or evidence of continued disease within five years before starting study drug Patients who have been taking domperidone at a dose level of more than 30 mg/day since before the preliminary evaluation Patients who do not test negative in the direct Coombs' test as part of the preliminary evaluation Pregnant or lactating women, women who are planning to have children, women who test positive in the pregnancy test during the preliminary evaluation or on Day -1, or women who cannot adhere to a reliable method of contraception throughout the study Patients who have received MAO inhibitors except selegiline within three months before starting study drug