A drug that blocks the action of glutamate, an amino acid in the brain that functions as a neurotransmitter that stimulates general activity in brain neurons, possibly hastening their death and contributing to the progression of Parkinson’s disease. Extending a neuro-protective effect, glutamate antagonists prevent glutamate from binding with glutamate receptors in various neurons. This action also helps to relieve some of the motor symptoms of Parkinson’s. The NMDA type of glutamate receptor has attracted the most attention, and clinically available glutamate antagonists block the NMDA type of glutamate receptor.
Glutamate antagonists generally are more effective when taken as one of the adjunct therapiEs to lEvodopa treatment. The exception is amantadinE, an antagonist of glutamate taken early in the course of Parkinson’s, which often is effective at controlling tremors, bradykinEsia, and other motor symptoms of Parkinson’s for about a year and sometimes as long as three years, delaying the need to begin levodopa. Amantadine also is effective in mid to later stages of Parkinson’s as an adjunct therapy to either levodopa or dopamine agonists. Riluzole, a glutamate antagonist that has some evidence that it may prolong survival in amyotrophic lateral sclerosis, is currently being investigated for possible neuropro-tective effects in people with Parkinson’s. The other glutamate antagonist currently used to treat the symptoms of Parkinson’s disease is rEmacEmidE, a drug that first came into use as an antiseizure MEDICATION.