U50844H

U50844H is a selective kappa opioid receptor (KOR) agonist belonging to the arylacetamide class of compounds. Developed by the Upjohn Company (now part of Pfizer) in the late 1970s, it is a structural analog of the prototypical KOR agonist U-50488H. Chemically, U50844H is the methanesulfonate salt of the 4-monochloro derivative of the benzeneacetamide scaffold, whereas U-50488H is the 3,4-dichloro derivative. In preclinical pharmacological studies, U50844H demonstrated high affinity and selectivity for the kappa receptor over mu and delta opioid receptors. It produces characteristic KOR-mediated physiological effects in animal models, including analgesia, diuresis, and sedation. While it served as a critical tool for mapping the structure-activity relationships of the arylacetamide series and understanding the biology of kappa opioid signaling, U50844H was not advanced into clinical development and remains a research-grade chemical.

Other names

trans-(±)-4-chloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide methanesulfonate