MT-1 (Melanotan I)

MT-1 — also known as Melanotan-1 and afamelanotide — is a synthetic 13-amino-acid analogue of naturally occurring alpha-melanocyte-stimulating hormone (α-MSH). It was developed as a more stable, longer-acting derivative designed to activate melanocortin receptors and drive melanin synthesis in the skin. Unlike alpha-MSH itself, which has a plasma half-life of only a few minutes, afamelanotide is metabolically resistant to rapid enzymatic degradation. The compound achieved regulatory approval under the brand name Scenesse (Clinuvel Pharmaceuticals) — first in Italy and Switzerland (2010), then across the European Union via EMA approval (January 2015), and finally in the United States (FDA, October 2019). All approvals are for a single indication: reducing phototoxic pain in adults with erythropoietic protoporphyria (EPP), a rare inherited disorder in which accumulated protoporphyrin IX causes severe burning pain on light exposure. The approved formulation is a controlled-release subcutaneous implant delivering 16 mg afamelanotide over approximately 60 days. MT-1 is meaningfully different from Melanotan II (MT-2). MT-1 is highly selective for MC1R, the receptor found on melanocytes, and does not substantially activate MC3R or MC4R — the receptors responsible for MT-2's libido effects, spontaneous erections, nausea, and appetite suppression. This selectivity makes MT-1's side-effect profile substantially cleaner in clinical trials, with nausea and headache as the most common events, but without the sexualised and appetite-related effects associated with MT-2. Beyond EPP, afamelanotide has been investigated in Phase II trials for polymorphous light eruption, solar urticaria, actinic keratosis prevention in organ-transplant recipients, vitiligo, and acne vulgaris. Results in polymorphous light eruption showed promise, but phase III trials for most indications outside EPP have not followed. In the research and fitness community, injectable MT-1 (lyophilised powder reconstituted with bacteriostatic water) is used off-label for cosmetic tanning. This is unregulated, unapproved use. Research-use material is not subject to the manufacturing quality controls that govern Scenesse implants.