Salvinorin A, a diterpene from Salvia divinorum, is a high-affinity and selective full agonist at human kappa-opioid receptors. In human embryonic kidney-293 cells, salvinorin A fully inhibited forskolin-stimulated cAMP production, while derivatives like 2-propionate and 2-heptanoate were partial agonists. Further tests using chimeric G proteins confirmed its potency and efficacy. In Xenopus oocytes with minimal receptor reserve, salvinorin A acted as a full agonist, more efficacious than standard agonists U50488 and U69593, and similar to dynorphin A. The 2-position substituent is critical for receptor binding and activation. Salvinorin A is the first known naturally occurring non-nitrogenous full agonist at kappa-opioid receptors.
The authors argue that the term "dissociative" is outdated and imprecise for describing the subjective effects of ketamine and related drugs. Originally coined in 1966 to describe feelings of being in outer space or lacking limbs, the term does not capture the full range of psychedelic experiences measured by modern rating scales like the Bowdle Visual Analogue Scale and Hallucinogen Rating Scale. The authors suggest that drugs such as phencyclidine, dextromethorphan, salvinorin A, and nitrous oxide—often grouped as "dissociative anesthetics"—produce subjective effects that are not identical to each other and can resemble those of classic psychedelics like dimethyltryptamine or psilocybin. They recommend describing these drugs primarily by their mechanism of action, such as "the NMDA antagonist ketamine," rather than by the term dissociative.