Melanotan II

A cyclic heptapeptide analog of alpha-MSH that non-selectively activates multiple melanocortin receptors (MC1R-MC5R). It produces skin tanning, appetite suppression, and notably strong pro-erectile and pro-sexual effects via MC3R/MC4R activation. While widely used in the cosmetic and bodybuilding communities for tanning, its cross-reactivity makes it a dual cosmetic/sexual-health peptide.

• Activates MC1R to stimulate melanocyte melanin production
• Activates MC3R and MC4R in the hypothalamus to modulate sexual arousal and appetite
• Increases cAMP in melanocytes leading to tyrosinase activation
• Crosses the blood-brain barrier to exert central nervous system effects on libido

• History of melanoma or dysplastic nevus syndrome
• Cardiovascular disease or uncontrolled hypertension
• Priapism or conditions predisposing to priapism
• Pregnancy or breastfeeding
• Concurrent use of PDE5 inhibitors (increased priapism risk)

Store at 2–8°C (36–46°F) for up to 3 months, protected from light. Once reconstituted, refrigerate and use within 21-28 days. Extremely light-sensitive.

Developed at the University of Arizona in the 1990s, Melanotan II was initially researched for tanning and later for sexual dysfunction. Its pro-erectile effects led to the development of bremelanotide (PT-141), which received FDA approval. MT-II itself remains unregulated and is widely available through research chemical suppliers. Safety concerns center around mole changes and potential melanoma promotion, though no causal link has been established. Regulatory agencies in Australia and Europe have issued warnings about unregulated use.