Melanotan II

Synthetic α-MSH analog that induces genuine tanning without UV exposure. Non-selective melanocortin agonist with additional effects on sexual function and appetite.

Overview

Also Known As

MT-II, MT-2, Melanotan 2, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2

Mechanism of Action

Non-selective melanocortin receptor agonist. MC1R: stimulates eumelanin production (tanning). MC4R: stimulates sexual arousal, suppresses appetite. MC3R: modulates energy balance. Produces genuine photoprotective eumelanin pigmentation.

Product

MT-II, MT-2, Melanotan 2, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 vial

Dosing & Administration

Typical protocols and routes

Half-Life

Approximately 1-2 hours

Administration Routes

subcutaneousintranasal

Dosing Protocols

Provider protocol: Start at approximately 0.167 mg subcutaneous, 2 times per week. Reconstitute 10 mg vial with 3 mL bacteriostatic water, draw 5 units on a 100-unit insulin syringe per dose. Increase only if well tolerated, on a per-person basis. Some research protocols describe a loading phase of 0.25-0.5 mg daily for 2-3 weeks, but the provider recommends a more conservative start.

Research

Key findings and status

Key Research Findings

Dorr et al. (1996, Arch Dermatology): clinical trial demonstrating significant tanning without UV. Led to development of PT-141 (FDA-approved as Vyleesi for HSDD, 2019). Investigated for melanoma prevention in high-risk fair-skinned populations.

Detailed Information

Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH) developed at the University of Arizona. Originally designed as a sunless tanning agent, MT-II is a non-selective melanocortin receptor agonist that activates MC1R (skin pigmentation), MC3R (energy homeostasis), MC4R (sexual function and appetite), and MC5R (exocrine secretion). This broad receptor profile gives it diverse physiological effects.

Mechanism of Action

Melanotan II activates melanocortin receptors throughout the body. At MC1R on melanocytes, it stimulates eumelanin production, resulting in skin darkening (tanning) without UV exposure. At MC4R in the hypothalamus, it stimulates sexual arousal and penile erection (this effect led to the development of PT-141/bremelanotide as a targeted sexual dysfunction drug) while simultaneously suppressing appetite. At MC3R, it modulates energy balance and fat metabolism.

The tanning effect develops gradually over days to weeks and persists for weeks to months after discontinuation, as melanin turnover in skin is slow. The tan produced is genuine eumelanin-based (the same pigment as natural tanning) and provides actual photoprotective benefit, unlike topical bronzers.

Research Context

While MT-II has undergone clinical trials for erectile dysfunction and tanning, regulatory development focused on the more selective derivative PT-141 (bremelanotide), which was FDA-approved as Vyleesi® in 2019 for hypoactive sexual desire disorder. MT-II itself has not received regulatory approval due to its non-selective receptor profile and associated side effects (nausea, facial flushing, spontaneous erections).

Dorr et al. (1996, Archives of Dermatology) conducted the pivotal clinical trial demonstrating that subcutaneous MT-II induced significant skin darkening without UV exposure. Subsequent research has explored its potential for preventing UV-induced skin cancer in fair-skinned populations at high melanoma risk.

Safety & Legal

Side Effects & Warnings

Nausea (common, especially initially), facial flushing, fatigue, spontaneous erections, appetite suppression, darkening of existing moles (requires monitoring), injection site reactions. Rare: priapism. Concern: potential for promoting melanoma in pre-existing atypical nevi.

Legal Status

Research use only. PT-141 derivative is FDA-approved as Vyleesi.

Molecular Data

Chemical properties

Molecular Weight

1024.18 g/mol

Amino Acid Sequence

Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2