Melanotan I

A linear synthetic analog of alpha-melanocyte-stimulating hormone (alpha-MSH) with substitutions at positions 4 (norleucine) and 7 (D-phenylalanine) that enhance potency and metabolic stability. Primarily targets MC1R for photoprotective tanning, with milder but documented effects on sexual function through partial MC4R activity.

• Potently and selectively agonizes MC1R on melanocytes, stimulating eumelanin synthesis via cAMP/PKA/MITF pathway
• Partial agonism at MC4R contributes to mild pro-sexual and anorexigenic effects
• Norleucine-4 and D-Phe-7 substitutions prevent oxidation and enzymatic degradation, increasing stability over native alpha-MSH

• History of melanoma or dysplastic nevus syndrome
• Severe hepatic impairment
• Pregnancy or breastfeeding
• Known hypersensitivity to afamelanotide

Store at 2–8°C (36–46°F) for up to 3 months. For long-term storage, keep at -20°C (-4°F). Once reconstituted, refrigerate and use within 28 days. Protect from light.

Reconstitute lyophilized research-grade peptide with bacteriostatic water. The FDA-approved form (Scenesse) is a subcutaneous implant that does not require reconstitution.

Afamelanotide (Melanotan I) was FDA-approved in October 2019 under the brand name Scenesse as a subcutaneous implant for the prevention of phototoxicity in adults with erythropoietic protoporphyria (EPP). It was previously approved in the EU in 2014. Clinical trials demonstrated significant increases in pain-free time in sunlight. Research has also explored its use in vitiligo, polymorphous light eruption, and actinic keratosis prevention. Its pro-sexual effects are milder than Melanotan II due to greater MC1R selectivity, but MC4R-mediated effects on libido have been documented.