Melanotan II

What it is

Melanotan II is a synthetic melanocortin receptor agonist, meaning it activates the receptors for melanocortin hormones such as alpha-MSH. It stimulates melanin production (tanning) and also affects libido and appetite. It is used recreationally despite its unregulated status, and a 2017 review described this unregulated use as appearing to increase.

In the PeptidesAI encyclopedia it is categorized under skin and anti-aging. It is related to Melanotan I (afamelanotide), which is the basis of an approved drug, but Melanotan II itself is not an approved medicine.

How it's thought to work

Melanotan II non-selectively activates melanocortin receptors. Activation of MC1R drives melanogenesis, the production of melanin that darkens skin, while activation of MC4R influences sexual arousal and appetite suppression.

What the research says

Melanotan II is not approved anywhere as a medicine; the related approved drug is afamelanotide (Scenesse) for a rare condition. Melanotan II itself is unregulated and not FDA-approved. Human data are limited and old: a 1996 pilot phase I study in three healthy male volunteers reported increased pigmentation in two of them, mild nausea and spontaneous erections, and a 1998 double-blind, placebo-controlled crossover study in 10 men with psychogenic erectile dysfunction reported erections in 8 of 10 men, with nausea, stretching and yawning, and decreased appetite reported more often than with placebo.

A 2017 review linked unregulated use of melanotan I and II to changes in existing moles and new atypical moles. It noted four case reports of melanomas emerging from existing moles, although conclusive evidence of a link is lacking, and that multiple national health organizations have issued safety warnings.

Reported side effects

Reported side effects include nausea, flushing, spontaneous erections, appetite suppression, and darkening of moles and new pigmented spots. Concerns about melanoma have been raised, because case reports describe melanomas arising from existing moles in people who used melanotan products, although a causal link has not been established.

Reconstitution

Melanotan II is supplied as a lyophilized (freeze-dried) powder and is typically reconstituted with bacteriostatic (BAC) water before use. It commonly comes in 10 mg vials. The amount of peptide in the vial is fixed; the water added only changes how concentrated the solution is.

Worked example. A 10 mg vial is 10,000 mcg. Reconstituted with 2 mL of BAC water, that works out to 10,000 mcg ÷ 2 mL = 5,000 mcg/mL. On a U-100 insulin syringe, where each unit is 0.01 mL, each unit holds 5,000 × 0.01 = 50 mcg. Use the peptide reconstitution calculator to work out the concentration and units for any vial size and water volume.

Important notes

Melanotan II is not FDA-approved. It causes mole and skin darkening, so skin changes are a recognized concern. The purity of unregulated product is a real concern, and a 2017 review raised questions about the preparation, administration and dosage of these unregulated substances.

Sources

1. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Dorr RT et al. Life Sci, 1996. Human trial
2. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. Wessells H et al. J Urol, 1998. Human trial
3. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Habbema L et al. Int J Dermatol, 2017. Review

How we choose and check sources

Frequently asked questions

These questions cover the same ground as the sections above, in a shorter format.

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