Glutamate Blocker
Summary:
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.
Potential benefits:
- Reduced dyskinesias
- AMPA receptor antagonists may be neuroprotective
Current
research:
Talampanel (Kinampa) is in Phase II trials to treat dyskinesia
associated with Parkinson's disease
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