RB-64
RB-64 or 22-thiocyanatosalvinorin A is a semi-synthetic salvinorin derivative and a κ-opioid receptor agonist which is used in scientific research. Its most remarkable property is its biased activity in signal transduction in favour of G protein versus β-arrestin-2, a phenomenon which is called functional selectivity or biased agonism. RB-64 has a bias factor of 96 and is analgesic with fewer of the prototypical side-effects associated with unbiased KOR agonists. The analgesia-like effect is long-lasting. Compared with unbiased agonists RB-64 evokes considerably less receptor internalisation.
