6'-Guanidinonaltrindole (6'-GNTI) is a κ−δ-opioid receptor selective ligand used in scientific research.
With 6'-GNTI, evidence was provided for the first time that receptor oligomizeration plays functional role in living organisms.
6'-GNTI is an extremely biased agonist of the κ-opioid receptor. It is a potent partial agonist of the G protein pathway but does not recruit the β-arrestin pathway. Due to its functional selectivity for the G protein pathway, 6'-GNTI functions as an antagonist of nonbiased KOR agonists on the β-arrestin pathway. It is thought that 6'-GTNI may be able to produce analgesia without dysphoria and with a lower incidence of tolerance.