ketanserin + psilocybin

Ketanserin + psilocybin is an experimental drug combination consisting of ketanserin, a selective serotonin 2A/2C receptor (5-HT2A/2C) antagonist, and psilocybin, a prodrug for the psychedelic compound psilocin which acts as a potent agonist at the serotonin 2A receptor. This combination is primarily used in research settings to investigate the role of 5-HT2A receptor activation in mediating both the subjective and neurophysiological effects of psychedelics. Ketanserin is administered to block or attenuate the effects induced by psilocybin, allowing researchers to dissect which outcomes are specifically mediated by 5-HT2A signaling. Studies have shown that ketanserin can neutralize or significantly reduce many of the acute perceptual and cognitive alterations produced by psilocybin without having significant psychoactive effects on its own[3][6][4]. The combination has been studied in healthy volunteers for its impact on cerebral blood flow, sensorimotor gating, attentional control, and other neuropsychological parameters[1][8]. Preclinical studies suggest that some antidepressant-like actions of psilocybin may persist even when 5-HT2A receptors are blocked by ketanserin[4][5].