Sponsor withdrew support

The study will involve an eighteen-week, double-blind, placebo-controlled parallel designed comparison between add-on topiramate and add-on placebo to stable treatment with amatadine in the treatment of Parkinson's disease (PD) patients who continue to have dyskinesia on amantadine.

We conducted a randomized placebo controlled trial of topiramate in PD dyskinetic subjects already on amantadine but with continuing dyskinesia. Topiramate or placebo was introduced in blinded fashion with a gradual titration (topiramate 25-150 mg/d) over 6 weeks and then a maintenance period of 8 weeks. The primary outcome of interest was change from baseline to end of study in total Unified Dyskinesia Rating Scale (UDysRS) score using Intention to Treat analysis.

Inclusion Criteria:

1. Parkinson's disease patient, defined by United Kingdom (UK) Brain Bank criteria
2. Current age between 30-90
3. Clinically pertinent dyskinesias defined by Clinical Global Impression - Severity (CGI-s) score (see attachment) > 3 (mild) established by clinician's total assessment of patient including objective observation during the screening process. *
4. Stable doses of all antiparkinsonian medications for at least 4 weeks
5. Stable treatment with at least 200 mg amantadine for at least 4 weeks.
6. Presence of a caregiver willing to participate in the study
7. In the opinion of the enrolling investigator, the subject will be able to maintain current dosing schedule of antiparkinsonian drugs for the duration of the trial.
8. Subjects must be free of dementia, depression and psychosis as determined by clinical examination.
9. The subject must be willing to participate in all study related activities and visits.

Exclusion criteria:

1. Any subjects with clinical evidence suggestive of an atypical or secondary form of Parkinson's Disease
2. Any subject who, in the opinion of the Principal Investigator, has a concomitant medical illness which would preclude them from being treated with amantadine,
3. Any subject who, in the opinion of the Principal Investigator, will be unable to maintain current stable dosing of their anti-parkinsonian medications for the duration of the trial,
4. Any subject with evidence for dementia, depression, or psychosis, as determined by clinical examination.
5. Any subject who has not signed informed consent, or unable or unwilling to participate in all of the study related activities.