A Glutamate N-Methyl-d-Aspartate (NMDA) Receptor Subunit 2B-Selective Inhibitor of NMDA Receptor Function with Enhanced Potency at Acidic pH and Oral Bioavailability for Clinical Use

J Pharmacol Exp Ther. 2021 Oct;379(1):41-52. doi: 10.1124/jpet.120.000370. Epub 2021 Sep 7.


We describe a clinical candidate molecule from a new series of glutamate N-methyl-d-aspartate receptor subunit 2B-selective inhibitors that shows enhanced inhibition at extracellular acidic pH values relative to physiologic pH. This property should render these compounds more effective inhibitors of N-methyl-d-aspartate receptors at synapses responding to a high frequency of action potentials, since glutamate-containing vesicles are acidic within their lumen. In addition, acidification of penumbral regions around ischemic tissue should also enhance selective drug action for improved neuroprotection. The aryl piperazine we describe here shows strong neuroprotective actions with minimal side effects in preclinical studies. The clinical candidate molecule NP10679 has high oral bioavailability with good brain penetration and is suitable for both intravenous and oral dosing for therapeutic use in humans. SIGNIFICANCE STATEMENT: This study identifies a new series of glutamate N-methyl-d-aspartate (NMDA) receptor subunit 2B-selective negative allosteric modulators with properties appropriate for clinical advancement. The compounds are more potent at acidic pH, associated with ischemic tissue, and this property should increase the therapeutic safety of this class by improving efficacy in affected tissue while sparing NMDA receptor block in healthy brain.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acids
  • Administration, Oral
  • Animals
  • Biological Availability
  • Brain / drug effects*
  • Brain / metabolism*
  • Dose-Response Relationship, Drug
  • Excitatory Amino Acid Antagonists / administration & dosage*
  • Excitatory Amino Acid Antagonists / metabolism*
  • Female
  • Hydrogen-Ion Concentration
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors*
  • Receptors, N-Methyl-D-Aspartate / metabolism*
  • Xenopus laevis


  • Acids
  • Excitatory Amino Acid Antagonists
  • NR2B NMDA receptor
  • Receptors, N-Methyl-D-Aspartate