Melanotan I (Afamelanotide)
A synthetic analogue of alpha-melanocyte-stimulating hormone (α-MSH) that binds the melanocortin-1 receptor to stimulate eumelanin production. Licensed as afamelanotide (Scenesse) via a slow-release implant for erythropoietic protoporphyria (EPP), a rare light-sensitivity disorder. Distinct from the more androgenic, appetite/erection-affecting Melanotan II.
01 Overview
Melanotan I is a linear 13-amino-acid analogue of α-MSH designed to resist enzymatic degradation, giving it a longer duration than the native hormone. Its pharmaceutical form, afamelanotide, is delivered as a subcutaneous bioresorbable implant and is approved in the EU and US for reducing phototoxic reactions in adults with EPP. It increases skin eumelanin independently of UV exposure, offering photoprotection.
Outside its licensed indication, Melanotan I is sold in grey-market injectable powders for cosmetic tanning. Unlike Melanotan II it is MC1R-selective and largely lacks the MC3/MC4-mediated effects on libido and appetite. The clinical afamelanotide data are solid; the self-administered tanning use is far less characterised and carries the usual sterility and dosing risks of unregulated peptides.
02 Mechanism
Agonist at the melanocortin-1 receptor (MC1R) on melanocytes, upregulating tyrosinase and shifting melanin synthesis toward photoprotective eumelanin.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Grey-market tanning (unlicensed) | 0.5–1 mg/day | SubQ | Self-administered loading then maintenance; not a validated protocol. |
| Afamelanotide implant (licensed) | 16 mg | SubQ | One 16 mg controlled-release implant every ~2 months for EPP. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Increased skin pigmentationStimulates eumelanin independent of sun exposure, darkening skin and adding UV protection. | Measurable rise in melanin density | Clinical | |
| Reduced phototoxicity in EPPIn licensed use, lengthens the time EPP patients tolerate light before phototoxic pain. | More pain-free light exposure time | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Darkening of moles and frecklesExisting naevi darken and new pigmented spots may appear, complicating melanoma surveillance. | Mild | Common | Clinical | |
| Nausea and facial flushingTransient nausea, flushing and headache around administration. | Mild | Common | Clinical | |
| Injection-site and sterility risk (unlicensed powders)Grey-market reconstituted powder may be contaminated or misdosed, risking local reaction or infection. | Moderate | Unknown | Anecdotal |