Design and Synthesis of Novel Deuterated Ligands Functionally Selective for the γ-Aminobutyric Acid Type A Receptor (GABA A R) α6 Subtype with Improved Metabolic Stability and Enhanced Bioavailability

J Med Chem. 2018 Mar 22;61(6):2422-2446. doi: 10.1021/acs.jmedchem.7b01664. Epub 2018 Mar 6.

Abstract

Recent reports indicate that α6β2/3γ2 GABAAR selective ligands may be important for the treatment of trigeminal activation-related pain and neuropsychiatric disorders with sensori-motor gating deficits. Based on 3 functionally α6β2/3γ2 GABAAR selective pyrazoloquinolinones, 42 novel analogs were synthesized, and their in vitro metabolic stability and cytotoxicity as well as their in vivo pharmacokinetics, basic behavioral pharmacology, and effects on locomotion were investigated. Incorporation of deuterium into the methoxy substituents of the ligands increased their duration of action via improved metabolic stability and bioavailability, while their selectivity for the GABAAR α6 subtype was retained. 8b was identified as the lead compound with a substantially improved pharmacokinetic profile. The ligands allosterically modulated diazepam insensitive α6β2/3γ2 GABAARs and were functionally silent at diazepam sensitive α1β2/3γ2 GABAARs, thus no sedation was detected. In addition, these analogs were not cytotoxic, which render them interesting candidates for treatment of CNS disorders mediated by GABAAR α6β2/3γ2 subtypes.

Publication types

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

MeSH terms

  • Animals
  • Anti-Anxiety Agents / chemical synthesis
  • Anti-Anxiety Agents / pharmacology
  • Behavior, Animal / drug effects
  • Biological Availability
  • Deuterium
  • Drug Design
  • Female
  • GABA Antagonists / chemical synthesis*
  • GABA Antagonists / pharmacokinetics
  • GABA Antagonists / pharmacology*
  • HEK293 Cells
  • Humans
  • Hypnotics and Sedatives / pharmacology
  • Male
  • Maze Learning / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Microsomes, Liver
  • Motor Activity / drug effects
  • Muscle Strength / drug effects
  • Rats
  • Rats, Wistar
  • Receptors, GABA-A / drug effects*
  • Substrate Specificity

Substances

  • Anti-Anxiety Agents
  • GABA Antagonists
  • GABRA6 protein, human
  • Gabra6 protein, mouse
  • Hypnotics and Sedatives
  • Receptors, GABA-A
  • Deuterium