Inclusion criteria:

Subjects eligible for enrollment in the study must meet all of the following criteria. Note that both inpatients and outpatients are eligible.

• Patients with a diagnosis of PD (including juvenile parkinsonism) with Modified Hoehn & Yahr Stages I to IV.
• Patients who have been receiving another dopamine agonist for at least 4 weeks prior to the start of the screening phase and are expected to benefit from conversion to ReQuip.
• Age: 20 years (at the time of written informed consent).
• Informed consent: Patients who are able to give written informed consent in person (i.e., patients who are capable of giving written informed consent on their own).
• Gender: Male or female

Females of childbearing potential are eligible for enrollment in the study, only if the subject has a negative pregnancy test at the start of the screening phase and agrees to conduct pregnancy testing at the protocol-specified visits during the study and use one of the following acceptable methods of contraceptions properly and accurately:

• Abstinence
• Oral contraceptive, either combined or progestogen alone
• Injectable progestogen
• Implants of levonorgestrel
• Estrogenic vaginal ring (Caution: This should be used cautiously, because the blood concentration of the study drug may be increased.)
• Percutaneous contraceptive patches
• Intrauterine device (IUD) or intrauterine system (IUS) that meets the SOP effectiveness criteria as stated in the product label
• Male partner sterilization (vasectomy with documentation of azoospermia) prior to the female subject's entry into the study, and this male is the sole partner for that subject)
• Double barrier method: condom or occlusive cap (diaphragm or cervical / vault caps) plus spermicidal agent (foam/gel/film/cream/suppository)

Exclusion criteria:

Subjects meeting any of the following criteria must not be enrolled in the study:

• Patients who present with any serious medical condition other than PD (e.g., cardiac, hepatic or renal disorder or hematopoietic disorder).

Serious is defined as Grade 3 as a rule according to the Classification of the Severity of Adverse Experiences (PAB/SD Notification No. 80, dated 29 June 1992) .

• Patients with postural hypotension with any subjective symptoms (e.g., dizziness and syncope).
• Patients who have had any serious psychiatric symptoms (e.g., confusion, hallucination, delusion, abnormal behavior) (including symptoms caused by anti-PD drugs) within 6 months (26 weeks) prior to written informed consent.

• Patients who have initiated any of the following drugs within 4 weeks of the start of the screening phase and have the dosing regimen of the drug changed within 4 weeks of the start of the screening phase.

  • L-dopa (+DCI) (NOTE: This does not apply to the monotherapy group.)
  • Anticholinergic agents: trihexyphenidyl hydrochloride, piroheptine hydrochloride, mazaticol hydrochloride, metixene hydrochloride, biperiden, profenamine
  • amantadine hydrochloride
  • droxidopa
  • citicoline
  • selegiline hydrochloride
  • entacapone
  • zonisamide
• Patients with severe dementia with a Japanese UPDRS Part I (mentation, behavior, and mood) score of 3 or 4.
• Female patients who are pregnant or lactating, who may be pregnant, or who plan for pregnancy during the study period or within 30 days after the last dose of the study drug.
• Patients with a history of drug allergy to any ingredients of ReQuip.
• Patients who have received surgical treatment for PD in the past (e.g., pallidectomy, deep brain stimulation).
• Patients who have been treated with any other investigational product within 12 weeks prior to the start of the screening phase.
• Patients who, in the judgement of the investigator (or sub-investigator), have evidence of alcohol or drug abuse.
• Others whom the investigator (or sub-investigator) considers ineligible for the study.