In vitro pharmacological evaluation of the novel NOP receptor partial agonist sunobinop

Sleep-related disorders affect a significant portion of the global population. The nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor has become a promising candidate for the development of innovative drugs to treat sleep disorders. In this study, we conducted an in-depth pharmacological characterization of sunobinop, a selective NOP receptor partial agonist already under clinical evaluation for treating multiple conditions including insomnia, using a wide range of in vitro and ex vivo methodologies. Sunobinop exhibited partial agonist activity in calcium mobilization, NOP - G protein interaction, label-free bioimpedance, and cAMP inhibition assays. Notably, it demonstrated competitive antagonism in the NOP - β-Arrestin 2 recruitment and ex vivo electrically stimulated mouse Vas Deferens, assays characterized by low amplification. The findings reported here confirm and extend the characterization of sunobinop as a tool for studying NOP receptor pharmacology providing new insights into its mode of action, relevant to its clinical evaluation.