Like dopamine, glutamate is one of the brain's chemical messengers that allows neurons to communicate with each other. It is a neurotransmitter made up of very dissimilar properties. On one hand, its functioning allows us to move, feel and perceive. On the other hand, when it is imbalanced, it can trigger the death of neurons, which leads to cognitive and/or motor problems.
Scientists believe that excessive glutamate may play a role in causing the development of unwanted symptoms such as dyskinesia. When taking the glutamate blocker Amantadine (Symmetrel) for 15 days, people with Parkinson’s disease reduced their dyskinesias by 38%. When this compound was given to them intravenously, their dyskinesias improved by 50%. Unfortunately though, Amantadine does not work for everyone.
Only one glutamate blocker, Amantadine (Symmetrel®), is currently available for use by the general public. However other glutamate compounds are being developed, including remacemide, nemantadine, and riluzole (Rilutek®).
AMPA receptor (glutamate) antagonist
There are two receptors for glutamate. One is called the NMDA receptor and the other is called the AMPA receptor. (NMDA and AMPA are acronyms for two complex chemicals.) Until recently, there were only drugs that blocked the action of NMDA. Amantadine (Symmetrel), which can partially decrease or dampen dyskinesia, blocks the NMDA receptor. Memantine, a cousin of amantadine, which can partially improve thinking, behavior and memory in Alzheimer disease, blocks the NMDA receptor. Talampanel is the first drug used by people that blocks the AMPA receptor.
Talampanel was tested in a pilot study of 30 patients. Results indicate that it may be useful in decreasing or eliminating levodopa-induced dyskinesia. It is currently in a Phase II trial to treat dyskinesias in Parkinson’s disease.
Talampanel (Kinampa) is in Phase II trials to treat dyskinesia associated with Parkinson's disease
 Beyond Dopamine; by Lisa Melton PhD; 11-6-2004
 Minnesota Medicine: May 2001/Volume 84, Published monthly by the Minnesota Medical Association; Parkinson's Disease: An Overview of Treatment and Research; By Paul J. Tuite, M.D.
 Parkinson report, Vol. XIV, Issue 3 / Fall 2003, NPF; Talampanel in Parkinson Disease: Why the Excitement? By Dr. Abraham Lieberman
 Ask the Experts about Parkinson's Disease/Movement Disorders from Medscape Neurology & Neurosurgery Talampanel for PD-Related Dyskinesias, by J. Meyerson, MB, ChB, FRCPC