Kynurenate and FG9041 have both competitive and non-competitive antagonist actions at excitatory amino acid receptors.

The antagonist profile of kynurenate and FG9041 have been characterised in a modified preparation of the baby rat hemisected spinal cord. Both kynurenate and FG9041 were competitive antagonists of responses to kainate and AMPA, although neither antagonist was selective for kainate versus AMPA. In contrast, both antagonists produced an apparent unsurmountable antagonism of responses to NMDA, indicating a different mode of action at the NMDA receptor.