Educational reference, not medical advice. This page summarizes information from published research and regulatory filings for educational purposes. It is not a recommendation to use any compound and should not replace guidance from a licensed healthcare provider. Most peptides discussed here are not approved for the uses described.
What it is
Melanotan I — generic name afamelanotide, brand name Scenesse — is a synthetic 13-amino-acid analog of alpha-melanocyte-stimulating hormone (alpha-MSH) with two key modifications: a D-amino acid substitution at position 7 (D-Phe) and a norleucine at position 4. These changes make the molecule resistant to proteolytic degradation and substantially more potent than native alpha-MSH at the MC1 receptor on melanocytes.
Unlike most peptides in this library, Melanotan I is an approved drug and is delivered through an unusual route: a subcutaneous implant the size of a grain of rice placed every two months, rather than a daily injection.
History
The compound originated in the 1980s in the Mac Hadley and Victor Hruby labs at the University of Arizona as part of a research program on alpha-MSH analogs for sunless tanning. The original therapeutic hypothesis — that pre-emptive UV-independent skin pigmentation could reduce skin cancer risk — never produced an approved indication, but the chemistry was licensed to Clinuvel Pharmaceuticals (originally called EpiTan) for development.
Clinuvel pivoted the program toward rare photosensitivity disorders, principally erythropoietic protoporphyria (EPP), an autosomal dominant condition in which accumulation of protoporphyrin IX in the skin causes intense painful reactions to visible and ultraviolet light. Italian regulators (AIFA) granted the first national authorization in 2010 on compassionate-use grounds. The European Medicines Agency approved Scenesse in December 2014. The FDA approved Scenesse on October 8, 2019, following the publication of pivotal trial data including the multinational study reported in the New England Journal of Medicine in 2015.
Regulatory status
FDA approved October 8, 2019 as Scenesse for increasing pain-free light exposure in adults with a history of phototoxic reactions from EPP. EMA approved December 2014 for the same indication. Approved in Australia, Switzerland, and Israel for EPP.
Outside the EPP indication, afamelanotide is not approved. It is occasionally provided off-label for other photosensitivity disorders (notably Hailey-Hailey disease and vitiligo) through specialist centers; recreational tanning use is not within any approved label. Compounded "Melanotan I" sold through research peptide channels is not Scenesse — the implant formulation, dosing, and quality system are different.
Mechanism
Afamelanotide is a potent agonist at the MC1 receptor on melanocytes. Activation of MC1R drives eumelanin synthesis (the brown-black pigment) preferentially over pheomelanin (the red-yellow pigment). Eumelanin absorbs and scatters incident light across the UV and visible spectrum and provides better photoprotection at a given pigment quantity. In EPP, the increased eumelanin in the skin reduces the propagation of light to the dermal protoporphyrin-laden blood vessels that cause the phototoxic pain reaction.
There is also some activity at MC4 (central appetite and sexual function) and MC5 (sebaceous gland), but the modifications relative to native alpha-MSH bias the activity profile toward MC1.
Half-life and dosing intervals
Free circulating afamelanotide has a short plasma half-life — approximately 30 minutes to 1.7 hours depending on the assay. The clinically meaningful timescale is set by the implant rather than by the half-life of the free peptide.
Approved Scenesse dosing is one 16 mg subcutaneous implant placed in the suprailiac region every 2 months. The implant releases afamelanotide over approximately 2 days, but the resulting melanogenesis persists for the full 2-month interval before the next implant is required.
Reconstitution example
Scenesse is supplied as a pre-formed solid implant — there is no reconstitution. The implant is inserted by a trained clinician using a specialized trocar; this is not a self-administered medication. Compounded "Melanotan I" sold through research channels is typically a lyophilized powder for subcutaneous injection: a 10 mg vial reconstituted with 2 mL of bacteriostatic water yields 5 mg/mL. On a 1 mL U-100 insulin syringe, 20 units (0.2 mL) delivers 1 mg. This injectable form is not Scenesse and is not authorized for clinical use.
What to know
- Approved for a rare disorder. Scenesse is approved for erythropoietic protoporphyria, not for tanning or general dermatology. The approved population is small (estimated 5,000 to 10,000 EPP patients in the EU and US combined).
- Implant, not injection. The approved product is a slow-release subcutaneous implant placed by a clinician. Compounded "Melanotan I" injection is a different product.
- Distinct from Melanotan II. Melanotan I (afamelanotide) is approved. Melanotan II is not approved anywhere and was abandoned by Clinuvel in the 2000s due to the off-target MC4 activity that drives sexual side effects and nausea.
- Common reported side effects. In trials: implant-site reactions, headache, nausea, fatigue. The expected and intended effect is darkening of skin, gums, and existing moles; the change is reversible after discontinuation but takes months to fade.
- Skin cancer surveillance. The FDA label recommends a full-body skin examination twice yearly because afamelanotide induces darkening of existing moles, which complicates dermatologic surveillance.
- Storage. Implants are refrigerated until use. Compounded lyophilized injectable: refrigerate before and after reconstitution.
Sources
- 1.Langendonk JG et al. (2015). Afamelanotide for Erythropoietic Protoporphyria. New England Journal of Medicine.
- 2.Kim ES, Garnock-Jones KP (2016). Afamelanotide: A Review in Erythropoietic Protoporphyria. American Journal of Clinical Dermatology.
- 3.Wensink D et al. (2021). Afamelanotide for prevention of phototoxicity in erythropoietic protoporphyria. Expert Review of Clinical Pharmacology.
- 4.Minder EI, Schneider-Yin X (2015). Afamelanotide (CUV1647) in dermal phototoxicity of erythropoietic protoporphyria. Expert Review of Clinical Pharmacology.