Effects of Talampanel on Patients With Advanced Parkinson's Disease

Effects of Talampanel on Patients With Advanced Parkinson's Disease Who Have Been on Sinemet for More Than 5 Years and Have Dyskinesia (Abnormal Involuntary Movements)

The purpose of this research study is to test the safety and effectiveness of the study drug, Talampanel, when used to treat patients with involuntary movements known as dyskinesias, as a result of treatment to Parkinson's disease.

It is not clear why people with Parkinson's disease develop involuntary movements (dyskinesias) but studies show that blocking receptors in the brain for a chemical called glutamate decreases these movements. Talampanel is a drug which blocks these receptors.

Inclusion Criteria:

• Troublesome on-period dyskinesias as defined by a Unified Parkinson's Disease Rating Scale (UPDRS) dyskinesia sub-score >25% of Duration of dyskinesia during waking hours and 33 must have moderate disability
• Lang-Fahn dyskinesia rating score more than 2 for at least two of the 5 tasks
• Must have Dyskinesia on average 25% of waking hours/day based on Patient Diaries
• Have been diagnosed with Parkinson's disease > 5 years at Screening

Exclusion Criteria:

• Previous surgical therapies for PD
• Isolated or predominantly diphasic dyskinesias
• Moderate Dementia
• On disallowed concomitant medications including CYP3A4 inhibitors and inducers, amantadine, etc.