What Is Melanotan II?
Melanotan II is a cyclic synthetic heptapeptide analog of α-MSH that differs from its linear cousin Melanotan I in both structure and receptor selectivity profile. Its cyclic structure confers greater metabolic stability, and its selectivity profile — spanning MC1R, MC3R, and MC4R — produces a broader range of biological effects including potent melanogenesis, appetite suppression, and pro-erectile/pro-libido effects that have driven its primary use in research.
Pro-Erectile and Libido Mechanisms
MC4R (melanocortin receptor 4) is expressed in hypothalamic and brainstem nuclei governing sexual arousal and erectile function. Melanotan II's MC4R activation initiates central pro-erectile pathways — increasing oxytocin release and downstream dopaminergic activation — that can produce spontaneous erections in male research subjects independent of tactile stimulation. This central mechanism distinguishes it from phosphodiesterase inhibitors (sildenafil, etc.) which work peripherally on penile vasodilation.
PT-141 Derivation and Side Effects
PT-141 (Bremelanotide) was derived directly from Melanotan II by identifying the active pharmacophore for sexual function while removing the melanogenic activity. Melanotan II's side effects include pronounced melanogenesis affecting nevi (moles) that should be monitored, nausea, facial flushing, and spontaneous erections — all dose-dependent and transient.
Quick Reference
Member reference tables summarize the compound's research parameters.
Research Indications
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below), not a personal dosing recommendation.
This member section describes parameters reported in the research literature.
Peptide Interactions
This member section summarizes reported compound interactions and evidence limitations.
Reported Research Time Points
This member section summarizes reported research time points.
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
This member section discusses research safety considerations and uncertainties.
Quality Indicators
Research Citations
- Cardiovascular Effects Assessment (2018)
Human | Various doses | Acute monitoring | Mild BP elevation - Photoprotection in Fair-Skinned Individuals (2015)
Human (Fitzpatrick Type I-II) | 0.1mg/kg | 3 months | Reduced sunburn incidence - Female Sexual Arousal Disorder Trial (2004)
Human (Female) | 0.025mg/kg | Single dose | 73% reported arousal - Appetite and Food Intake Study (2001)
Human | 1mg daily | 6 weeks | 15% reduction in caloric intake - Phase II Trial of Melanotan II in Erectile Dysfunction (2000)
Human | 0.025mg/kg | 3 months | 80% response rate - Melanogenesis and UV Protection Study (1999)
Human | 0.16mg/kg daily | 10 days | Increased melanin density - 5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II
Todorovic M, Blanc A, Wang Z, 2024, Chemistry - Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study
Dorr RT, Lines R, Levine N, 1996, Life Sci - CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists
Tomassi S, Dimmito MP, Cai M, 2022, J Med Chem - Combining MALDI mass spectrometry imaging and droplet-base surface sampling analysis for tissue distribution, metabolite profiling, and relative quantification of cyclic peptide melanotan II
Chen B, Vavrek M, Gundersdorf R, 2020, Anal Chim Acta - A liquid chromatographic/tandem mass spectroscopic method for quantification of the cyclic peptide melanotan-II. Plasma and brain tissue concentrations following administration in mice
Hatziieremia S, Kostomitsopoulos N, Balafas V, 2007, Rapid Commun Mass Spectrom