What are the mechanisms of action and pharmacokinetics of glutamate receptor blockers?

Updated: Jan 28, 2020
  • Author: Juan G Ochoa, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Answer

Glutamate receptors bind glutamate, an excitatory amino acid neurotransmitter. Upon binding glutamate, the receptors facilitate the flow of both sodium and calcium ions into the cell, while potassium ions flow out of the cell, resulting in excitation.

The glutamate receptor has 5 potential binding sites, as follows:

  • The alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) site

  • The kainate site

  • The N -methyl-D-aspartate (NMDA) site

  • The glycine site

  • The metabotropic site, which has 7 subunits (GluR 1-7)

AEDs that modify these receptors are antagonistic to glutamate (see the images below). Responses to glutamate antagonists differ, depending on the site being affected.

Glutamate (main excitatory neurotransmitter in cen Glutamate (main excitatory neurotransmitter in central nervous system) binds to multiple receptor sites that differ in activation and inactivation time courses, desensitization kinetics, conductance, and ion permeability. Three main glutamate receptor subtypes are N-methyl-D-aspartate (NMDA), metabotropic, and non-NMDA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid [AMPA] and kainate receptors). Antiepileptic drugs known to possess this mechanism of action are listed.
Schematic representation of N-methyl-D-aspartate ( Schematic representation of N-methyl-D-aspartate (NMDA) receptor.

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