Melanotan IIAlso known as: Melanotan-2, MT-II, Melanotan-2 acetate

Mechanism of Action

Melanotan II is a synthetic peptide analogue of the α-melanocyte stimulating hormone (α-MSH). It activates melanocortin receptors, primarily MC1R in the skin to stimulate melanogenesis (melanin production), producing skin pigmentation without UV exposure. It also activates MC4R centrally in the brain to influence sexual arousal, appetite regulation, mood, and energy homeostasis. This dual peripheral and central receptor activation distinguishes its pharmacodynamics.

Reported Research Benefits

Used primarily in preclinical and laboratory research to study skin pigmentation modulations, UV protection mechanisms, sexual behavior and libido, mood alterations, and appetite control. It is investigated as a safer alternative to induce tanning and as a tool to explore melanocortin-related pathways in neurology and endocrinology.

Dosing Protocol & Reconstitution

Typically supplied as a lyophilized powder to be reconstituted in bacteriostatic water. In animal models and research settings, it is administered subcutaneously with dosing and frequency tailored to project goals, commonly once daily. Exact dosing depends on experimental design, though typical research doses range from microgram to milligram scale per injection. Refrigerated storage (2-8°C) after reconstitution is advised with stability up to 60 days.

Research Notes

Demonstrates efficient induction of eumelanin-based tanning without the need for UV radiation exposure. Preclinical data highlights its libido-enhancing effects mediated by central MC4R activation. The peptide shows a relatively short biological half-life (approx. 1-2 hours in vivo) necessitating repeat dosing in experimental protocols. Safety and efficacy continue to be subjects of ongoing research.

Research Summary

Melanotan II (MT-II) is a synthetic cyclic analog of alpha-MSH that binds melanocortin receptors (MC1R–MC5R) with high potency. It induces melanogenesis (skin darkening), and via MC4R activation produces potent aphrodisiac effects — it was the basis for the ED drug bremelanotide (PT-141). Animal studies also show appetite suppression and potential neuroprotective effects.

Side Effects & Safety

Significant nausea and flushing are common, especially on initial dosing. Spontaneous erections (priapism risk at higher doses), yawning, fatigue, and increased blood pressure reported. Facial flushing, darkening of existing moles, and potential formation of new nevi. Not approved for human use.

Stability & Storage

Refer to research notes

Molecular Data

Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2
Molecular Formula: C50H69N15O9
Molecular Weight: 1024.2 g/mol
CAS Number: 121062-08-6
IUPAC Name: Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH2 acetate

Primary literature: https://pubmed.ncbi.nlm.nih.gov/?term=Melanotan+II+melanocortin+tanning+libido