Melanotan II

A synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH) that activates multiple melanocortin receptors. Originally developed for skin tanning, it was found to produce significant pro-sexual effects, leading to the development of PT-141 (bremelanotide) as a more targeted derivative.

• Non-selectively agonizes melanocortin receptors MC1R (skin pigmentation), MC3R and MC4R (sexual function and energy homeostasis), and MC5R
• MC1R activation stimulates melanogenesis in melanocytes, increasing eumelanin production
• MC4R activation in hypothalamic and limbic circuits enhances sexual arousal and desire
• MC3R/MC4R activity in hypothalamic feeding centers contributes to appetite suppression

• History of melanoma or atypical mole syndrome
• Cardiovascular disease or uncontrolled hypertension
• Pregnancy or breastfeeding
• Autoimmune conditions affecting skin pigmentation

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 30 days. Protect from light.

Melanotan II was developed at the University of Arizona in the early 1990s as a photoprotective tanning agent. Phase I/II trials demonstrated effective tanning without UV exposure and revealed unexpected pro-sexual side effects, prompting development of the more selective PT-141. Due to its non-selective melanocortin activation and safety concerns around mole changes and melanoma risk, it has not pursued regulatory approval, though it remains widely available in research settings.