Abuse Liability and Anti‐Addiction Potential of the Atypical Mu Opioid Receptor Agonist IBNtxA

OBJECTIVE IBNtxA is a μ opioid receptor (MOR) agonist structurally related to the classical MOR antagonist naltrexone. Recent studies suggest IBNtxA preferentially signals through truncated MOR splice variants, producing a unique pharmacological profile resulting in potent analgesia with reduced side effects, including no conditioned place preference (CPP) when tested at a single dose. The purpose of this study is to 1) evaluate a range of IBNtxA doses to more fully assess its abuse liability and 2) determine the effects of IBNtxA on morphine CPP expression and reinstatement of morphine CPP. METHODS IBNtxA was synthesized and compared to morphine in standard CPP expression assays. Following morphine CPP training, IBNtxA was tested for its effects in inducing CPP reinstatement on its own or attenuating morphine‐primed reinstatement. Drug discrimination studies are also underway. RESULTS and CONCLUSIONS IBNtxA represents an intriguing lead compound for preclinical drug development specifically targeting MOR splice variants, potentially creating effective analgesics with reduced side effects. Furthermore, IBNtxA could have use as an adjunct therapy in agonist replacement strategies (e.g., methadone). Current collaborative efforts are aimed at developing novel analogues of IBNtxA for further analysis and understanding ligand‐receptor interactions across MOR splice variants using molecular modeling. Support or Funding Information Rowan University Seed Fund; travel support from Dean of Rowan University College of Science and Mathematics.