KB-128

KB-128 is a serotonin 5-HT₂ receptor modulator which is under development for the treatment of alcoholism (alcohol use disorder).^{[1][2][3][4][5]} Its route is unspecified.^[1]

The drug acts as a biased agonist of the serotonin 5-HT_2C receptor, with high G_q protein bias and minimal or negligible β-arrestin recruitment.^{[4][1][2][5][6]} It additionally acts as a silent antagonist of the serotonin 5-HT_2A and 5-HT_2B receptors.^{[4][1][2][5][6]} Due to its lack of activation of the serotonin 5-HT_2A and 5-HT_2B receptors, KB-128 is expected to lack hallucinogenic activity and cardiac valvulopathy risk, respectively.^[4][5][6] The drug has been reported to reduce alcohol consumption in rodents.^[4][7] It is being studied in terms of influence on methamphetamine-induced hyperactivity in rodents as well.^[8]

KB-128 is under development by Küleon Bioscience (formerly Psilosterics).^[1][2][3] It was first described by 2023.^[1][2][6] As of November 2025, the drug is in the preclinical research stage of development for treatment of alcoholism.^[1][2] There is also interest in KB-128 for potential treatment of various other conditions, including schizophrenia, Alzheimer's disease psychosis, depression, other addictions like stimulant use disorder, and obesity.^[5][6][2] KB-128 is listed on Psychedelic Alpha's drug development tracker and hence may be related to serotonergic psychedelics.^[3] The chemical structure of KB-128 does not yet appear to have been disclosed,^[1] though KB-128's structure is known to have been patented.^[4][9]

Besides KB-128, other candidates of Küleon Bioscience in earlier development include selective serotonin 5-HT_2A receptor agonists and mixed serotonin 5-HT_2A and 5-HT_2C receptor agonists, for instance non-hallucinogenic psychoplastogens.^[6][7] They have also patented many additional hallucinogenic and non-hallucinogenic compounds besides KB-128.^{[9][10][11][12]}