Source of Melanotan II

{{Infobox compound | name = Melanotan II | subtitle = Research peptide | Class = Melanocortin receptor agonist | Selectivity = Non-selective across MC1R, MC3R, MC4R, MC5R | Status = Not approved in any jurisdiction | Related approved compound = [[Bremelanotide]] (MC4R-directed) }} {{medical|talk=Unapproved-compound notice}} '''Melanotan II''' is a synthetic cyclic analogue of α-melanocyte-stimulating hormone and a non-selective agonist at melanocortin receptors. It is not approved in any jurisdiction and is distributed as a research chemical.{{r|hadley2005}} Non-selectivity is the defining property. Agonism at MC1R produces melanogenesis, the effect for which it is sought; agonism at MC4R affects appetite and sexual function; agonism at MC3R and MC5R contributes further effects. A single compound producing all of them simultaneously is a pharmacological blunt instrument.{{r|hadley2005}} Documented harms include nausea and vomiting, spontaneous erections, darkening and change of pigmented lesions, and case reports of melanoma diagnosed in users — the last of which is confounded by the underlying reason people seek tanning and by increased dermatological attention.{{r|cardones2009}} == Pharmacology == The melanocortin system comprises five receptors with distinct distributions. MC1R on melanocytes controls the switch between pheomelanin and eumelanin synthesis; MC4R in the hypothalamus is central to appetite regulation and is the target of approved anti-obesity compounds in rare genetic conditions. See [[Arcuate nucleus]].{{r|cone2005}} Melanotan II activates all of these. Selective compounds developed subsequently — [[Bremelanotide|bremelanotide]] for sexual dysfunction, and MC4R-directed agents for genetic obesity — represent the pharmacological correction of that non-selectivity.{{r|hadley2005}} Effects on appetite are real and are the reason the compound appears in weight-related discussion, but they are accompanied by every other melanocortin effect at the same time.{{r|cone2005}} == Documented harms == Nausea and vomiting are common and dose-related. Spontaneous erections are a predictable MC4R effect and were the observation that led to the development of bremelanotide.{{r|hadley2005}} Dermatological effects are the more consequential. Darkening of existing naevi, appearance of new pigmented lesions, and eruptive naevi have been reported, and there are case reports of melanoma in users. Whether the compound is causal is unestablished: users are self-selected for sun exposure and tanning behaviour, and increased dermatological surveillance in a population that has changed colour will find more lesions.{{r|cardones2009}} The honest position is that a mechanistic reason for concern exists — melanocyte stimulation — the case reports exist, and causation is not demonstrated.{{r|cardones2009}} == Status == Melanotan II is not approved anywhere and several regulators have issued warnings about products sold under the name. It is prohibited in competitive sport.{{r|hadley2005}} Material sold as melanotan II is subject to the same documentary considerations as any research peptide. It is a short cyclic peptide and therefore a simpler synthesis than the incretin analogues, though cyclisation adds its own impurity possibilities. See [[Certificate of analysis]] and [[Peptide content]].{{r|usp1503}} This wiki does not represent it as suitable for human use, and nothing here is medical advice. See [[Research use only]].{{r|reports}} == References == {{reflist}} <ref name="hadley2005">Hadley ME, Dorr RT. "Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization." ''Peptides'' 26(10):1687–1689 (2005). PMID 16112778.</ref> <ref name="cardones2009">Cardones AR, Grichnik JM. "α-Melanocyte-stimulating hormone-induced eruptive nevi." ''Archives of Dermatology'' 145(4):441–444 (2009). PMID 19380667.</ref> <ref name="cone2005">Cone RD. "Anatomy and regulation of the central melanocortin system." ''Nature Neuroscience'' 8(5):571–578 (2005). PMID 15856065.</ref> <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, ''Quality Attributes of Synthetic Peptide Drug Substances''.</ref> <ref name="reports">PeptidePedia Wiki community test-report tally, 2024–2026 (self-reported; see [[Project:Sourcing_guidelines]]).</ref> == See also == * [[Bremelanotide]] * [[Arcuate nucleus]] * [[Research use only]] * [[Certificate of analysis]] {{DEFAULTSORT:Melanotan II}} [[Category:Melanocortin agonists]] [[Category:Research peptides]] [[Category:Articles describing unapproved compounds]]