Highly Selective Dopamine D3 Receptor (D3R) Antagonists and Partial Agonists Based on Eticlopride and the D3R Crystal Structure: New Leads for Opioid Dependence Treatment

J Med Chem. 2016 Aug 25;59(16):7634-50. doi: 10.1021/acs.jmedchem.6b00860. Epub 2016 Aug 10.


The recent and precipitous increase in opioid analgesic abuse and overdose has inspired investigation of the dopamine D3 receptor (D3R) as a target for therapeutic intervention. Metabolic instability or predicted toxicity has precluded successful translation of previously reported D3R-selective antagonists to clinical use for cocaine abuse. Herein, we report a series of novel and D3R crystal structure-guided 4-phenylpiperazines with exceptionally high D3R affinities and/or selectivities with varying efficacies. Lead compound 19 was selected based on its in vitro profile: D3R Ki = 6.84 nM, 1700-fold D3R versus D2R binding selectivity, and its metabolic stability in mouse microsomes. Compound 19 inhibited oxycodone-induced hyperlocomotion in mice and reduced oxycodone-induced locomotor sensitization. In addition, pretreatment with 19 also dose-dependently inhibited the acquisition of oxycodone-induced conditioned place preference (CPP) in rats. These findings support the D3R as a target for opioid dependence treatment and compound 19 as a new lead molecule for development.

MeSH terms

  • Animals
  • Behavior, Animal / drug effects
  • Conditioning, Psychological / drug effects
  • Dopamine Antagonists / chemical synthesis
  • Dopamine Antagonists / chemistry
  • Dopamine Antagonists / pharmacology*
  • Dose-Response Relationship, Drug
  • HEK293 Cells
  • Humans
  • Locomotion / drug effects
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Structure
  • Opioid-Related Disorders / drug therapy*
  • Oxycodone
  • Rats
  • Rats, Long-Evans
  • Receptors, Dopamine D3 / agonists*
  • Receptors, Dopamine D3 / antagonists & inhibitors*
  • Salicylamides / chemical synthesis
  • Salicylamides / chemistry
  • Salicylamides / pharmacology*
  • Structure-Activity Relationship


  • Dopamine Antagonists
  • Receptors, Dopamine D3
  • Salicylamides
  • Oxycodone
  • eticlopride