PT-141 (bremelanotide; Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH) is a cyclic heptapeptide melanocortin receptor agonist derived from Melanotan II (MT-II), itself a cyclic analog of alpha-melanocyte-stimulating hormone (α-MSH). It was developed in the laboratory of Victor J. Hruby at the University of Arizona during investigations into the structure-activity relationships of melanocortin peptide analogs in the 1990s.

PT-141 acts as an agonist at MC3R and MC4R — centrally expressed melanocortin receptor subtypes present in the hypothalamus and limbic system — rather than via vascular smooth muscle mechanisms. Preclinical research by Diamond, Molinoff, and colleagues characterized receptor binding selectivity, functional cAMP signaling responses, and behavioral effects in rodent models. King and co-authors at the University of Arizona examined the compound’s effects on hypothalamic and limbic circuit activation parameters. All findings referenced here derive from preclinical models and have not been validated in controlled human clinical trials.

PT-141 research appears in International Journal of Impotence Research, Current Topics in Medicinal Chemistry, and Journal of Medicinal Chemistry. It is not approved by the U.S. Food and Drug Administration for any diagnostic, therapeutic, or preventive application in the research context. It is classified as a research compound only.