Melanotan I (afamelanotide) is a synthetic analogue of alpha-melanocyte-stimulating hormone (α-MSH) that acts as a non-selective agonist at melanocortin receptors, with particular affinity for MC1R — the receptor primarily responsible for controlling eumelanin production in skin melanocytes. By stimulating MC1R, Melanotan I accelerates the tanning response, producing increased melanin pigmentation even in the absence of UV radiation. It has been studied in dermatology research for photoprotective applications, particularly in conditions where UV sensitivity is a concern. Melanotan I does not significantly activate the MC3R and MC4R receptors associated with appetite and libido effects.