This study will evaluate the effects of the experimental drug talampanel on dyskinesias
(involuntary movements) that develop in patients with Parkinson's disease as a result of
long-term treatment with levodopa (Sinemet). The drug will be tested alone and in combination
with amantadine-a drug commonly used to alleviate dyskinesias.
Patients between 21 and 80 years of age with Parkinson's disease and dyskinesias may be
eligible for this study.
Screening and baseline evaluation. Participants are evaluated with a medical history,
physical and neurologic examinations, blood and urine tests, electrocardiogram (EKG) and
pregnancy test, if applicable. A chest x-ray and MRI or CT scan of the brain are done if
needed. Patients stop taking all antiparkinsonian medications for one month (2 months if
taking Selegiline) before the study begins and throughout its duration, except for certain
medicines allowed, including Sinemet, Mirapex and Requip. Amantadine can be taken up to 1
week before beginning the study.
Dose-finding phase. Patients are admitted to the NIH Clinical Center for 2 to 3 days for a
levodopa "dose-finding" procedure. For this test, patients stop taking Sinemet and instead
have it infused through a vein. During the infusions, the drug dose is increased slowly until
parkinsonian symptoms improve or unacceptable side effects occur or the maximum study dose is
reached. Symptoms are monitored frequently. At given times during the infusion, saline is
given instead of Sinemet. The infusions usually begin in the early morning and continue until
evening. Patients resume taking Sinemet between infusions. (Patients who have had dosing
infusions in the last 3 months do not have to undergo this phase of the study.)
After the dose-finding phase, patients are randomly assigned to take placebo (a "sugar pill")
or talampanel. Those taking talampanel also receive amantadine at their usual dosages. At
some point in the study, amantadine is replaced with placebo. Patients in the talampanel
group also receive placebo for portions of the study.
Active study phase. At study weeks 1, 5 and 7, patients are admitted to the Clinical Center
overnight for a levodopa infusion with talampanel or placebo. The day before the infusion,
patients have a brief physical examination, blood and urine tests, an EKG, and a review of
symptoms or changes in their condition. The next day, they receive an infusion of levodopa at
the dose determined in the dose-finding phase. Then they take a pill containing either
talampanel or placebo. Their parkinsonian symptoms and dyskinesias are evaluated and
videotaped every 30 minutes for about 6 hours. Blood is drawn and an EKG is obtained. At the
end of the infusions and ratings, patients resume their regular Parkinson's medications and
are given a new supply of study medications to take home.
At weeks 2, 3, 4 and 6, patients come to the Clinical Center for a review of drug side
effects. They have blood drawn and receive a new supply of study medications that last until
the next visit.
Follow-up. Two weeks after the study ends, patients are contacted by phone for a review of
side effects or they return to the clinic for an evaluation.
Phase:
Phase 2
Details
Lead Sponsor:
National Institute of Neurological Disorders and Stroke (NINDS)