GR-89696 is a drug which acts as a highly selective ú-opioid agonist. It has been studied in various animal species, and has been described as selective for the ú<sub>2</sub> subtype. Recent studies have suggested that GR-89696 and related ú<sub>2</sub>-selective agonists may be useful for preventing the itching which is a common side effect of conventional opioid analgesic drugs, without the additional side effects of non-selective kappa agonists. The structure bound to the ú-opioid receptor has been reported.