The primary purpose of this study is to measure the efficacy of solifenacin succinate (VESIcare) on treating urinary incontinence in Parkinson's disease patients.

The secondary objective of this study is to examine the effect of solifenacin succinate (VESIcare) on symptoms of PD and the patient's quality of life.

• Urinary Incontinence
• Parkinson's Disease

• Drug: Solifenacin Succinate (VESIcare)
• Drug: Placebo

Inclusion Criteria:

1. Outpatients with idiopathic PD according to the UK Parkinson's Disease Society Brain Bank Clinical Diagnosis Criteria.
2. Age 30 years to 80 years.
3. Stable dose of antiparkinsonian medication 4 weeks prior to study entry.
4. Patients must score 18 or higher on the UPDRS scale and 1.0 to 2.5 on the Modified Hoehn and Yahr scale.
5. Women of child-bearing potential must use a reliable method of contraception.
6. Must be experiencing symptoms of urinary incontinence (voiding 8 or more times/day or episodes of incontinence 5 or more times per week).
7. Patients must have evidence of normal PSA and urodynamic tests within the last 12 months.
8. Clearance from the patient's urologist or internist who has examined the patient within the last 12-months.

Exclusion Criteria:

1. Any illness that in the investigator's opinion preclude participation in this study.
2. Pregnancy or lactation.
3. Concurrent participation in another clinical study.
4. Dementia or other psychiatric illness that prevents the patient from giving informed consent (Mini Mental Status Exam score less than 24).
5. Legal incapacity or limited legal capacity.
6. Presence of severe renal disease (BUN 50% greater than normal).
7. Presence of major hepatic impairment.
8. Currently taking ketaconazole (anti-fungal) or any CYP3A4 inhibitor.
9. Any history of bladder outflow obstruction or gastrointestinal obstructive disorders.
10. History of controlled narrow angle glaucoma.