• Reduction of adverse event: [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Epworth Sleepiness Scale score for those with daytime sleepiness [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Neuropsychiatric Inventory Hallucinations question and Unified Parkinson's Disease Rating Scale Part I hallucinations question for those with hallucinations [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• circumference of lower leg/foot at greatest point of swelling for pedal edema [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Barratt Impulsiveness Scale for those with impulsive behavior [ Time Frame: 3 months ] [ Designated as safety issue: No ]

• Reduction of adverse event:
• Epworth Sleepiness Scale score for those with daytime sleepiness
• Neuropsychiatric Inventory Hallucinations question and Unified Parkinson's Disease Rating Scale Part I hallucinations question for those with hallucinations
• circumference of lower leg/foot at greatest point of swelling for pedal edema
• Barratt Impulsiveness Scale for those with impulsive behavior

• Maintenance of efficacy: [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Unified Parkinson's Disease Rating Scale Parts I-IV [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• PDQ-39 quality of life assessment [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Beck Depression Inventory and Beck Anxiety Inventory [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• patient and physician global impression of change [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Fatigue Severity Scale [ Time Frame: 3 months ] [ Designated as safety issue: No ]
• Mini-Mental State Examination [ Time Frame: 3 months ] [ Designated as safety issue: No ]

• Maintenance of efficacy:
• Unified Parkinson's Disease Rating Scale Parts I-IV
• PDQ-39 quality of life assessment
• Beck Depression Inventory and Beck Anxiety Inventory
• patient and physician global impression of change
• Fatigue Severity Scale
• Mini-Mental State Examination

The purpose of the study is to determine if reducing or eliminating a dopamine agonist causing one of the side effects of daytime sleepiness, swelling of the lower legs or feet, hallucinations or impulsive behaviors while adding orally disintegrating selegiline can eliminate the adverse effect and maintain control of Parkinson's disease symptoms.

Parkinson's disease (PD) is a progressive neurodegenerative disease. Symptomatic therapy is primarily aimed at restoring dopamine function in the brain. Levodopa is the most effective symptomatic treatment; however, long term use is associated with motor fluctuations (periods of return of PD symptoms when medication effect wears off) and dyskinesia (drug induced involuntary movements including chorea and dystonia). Once patients develop motor fluctuations treatment options include increasing the frequency of levodopa dosing, switching to sustained-release levodopa, adding other therapies including MAO-B inhibitors, dopamine agonists, COMT inhibitors and in patients with severe motor fluctuations deep brain stimulation surgery. There are no good evidence based studies indicating whether the use of one of these class of drugs is superior to the other nor are there treatment algorithms that recommend which class of drug should be initiated when the patients initially develop motor fluctuations. It is believed that the efficacy of the different drug classes is similar. However, the frequency of adverse effects may differ between drug classes, but such studies are lacking. In clinical practice when patients develop adverse effects to a drug from one class, a drug from another class is substituted in an attempt to maintain efficacy with reduced adverse effects.

Dopamine agonists often have a higher risk of adverse effects compared to MAO B inhibitors. Therefore, the rationale for this study is that the addition of orally disintegrating selegiline after the reduction or discontinuation of the offending dopamine agonist will result in comparable efficacy with reduced adverse events. This study will assess the safety and efficacy of the addition of orally disintegrating selegiline in PD patients who are having adverse effects to dopamine agonists for which a dose reduction of the dopamine agonist is being considered. All patients in the study will receive orally disintegrating selegiline 1.25 mg once a day and the dose will be increased to 2.5 mg once a day if tolerated.

Comparisons: The status of the adverse event at the end of the study while on orally disintegrating selegiline will be compared to the adverse event at the start of the study. In addition, efficacy will be compared at the start of the study while on the dopamine agonist to the end of the study with orally disintegrating selegiline.

Inclusion Criteria:

• Idiopathic PD confirmed by at least two of the following signs: resting tremor, bradykinesia,rigidity
• Male or female outpatients
• Age 30-90 years
• Current use of levodopa (stable for at least 1 month) and a dopamine agonist (pramipexole or ropinirole)
• Treatment response to current anti-parkinsonian medications in the opinion of the investigator
• Dopamine agonist adverse effect that in the opinion of the investigator requires a reduction or discontinuation of the dopamine agonist. The adverse effects must be in one of the following four categories and should not be so severe as to require immediate discontinuation of the dopamine agonist (i.e., hallucinations without insight, serious impulsive behavior resulting in significant loss or danger to the patient).

Daytime sleepiness - must score >10 on ESS at Baseline; Pedal edema - bothersome/concerning to patient; Hallucinations - insight should be maintained; Impulsive behavior - not including behaviors that are harmful to the patient requiring immediate discontinuation of the agonist.

• Daily off time
• Acceptable contraception for females of child bearing potential
• Willing and able to comply with study procedures.
• Willing and able to give written informed consent prior to beginning any study procedures.

Exclusion Criteria:

• Atypical parkinsonism due to drugs, metabolic disorders, encephalitis, trauma, or other neurodegenerative diseases.
• Significant cognitive or psychiatric impairment which, in the opinion of the investigator, would interfere with the ability to complete all the tests required in the protocol.
• Participation in another clinical drug trial within the previous four weeks.
• Patients currently on MAO-A or B inhibitors, meperidine, tramadol, methadone, propoxyphene, dextromethorphan, and mirtazapine.
• History of hypersensitivity or adverse reaction to selegiline or previous exposure to orally disintegrating selegiline
• History of melanoma
• Unstable/uncontrolled medical problems
• History of drug/alcohol abuse