Melanotan II
MT-2 · MT-II · Melanotan-2
- melanocortin
- tanning
- libido
- appetite
Melanotan II is a synthetic, non-selective melanocortin receptor agonist developed at the University of Arizona as a tanning agent. It activates MC1R, MC3R, MC4R, and MC5R with comparable affinity, producing skin pigmentation and, as an incidental finding in early trials, erectile/libido effects. It is not FDA-approved or approved by any regulatory agency for any use, and carries documented safety concerns distinct from its FDA-approved, more selective derivative bremelanotide (PT-141).
Melanotan II (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) is a cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH), originally developed as a potential skin-cancer-prevention strategy by inducing protective tanning without UV exposure. Unlike native alpha-MSH, which preferentially activates MC1R on melanocytes, MT-2 is non-selective and activates MC1R, MC3R, MC4R, and MC5R with broadly comparable affinity. This non-selectivity is clinically significant: MC4R activation in the hypothalamus and spinal cord drives the erectile/libido effect that emerged as an unanticipated finding in the first human pilot trials (and was later developed separately into the FDA-approved, more selective drug bremelanotide/PT-141), while MC3R/MC5R activation contributes to appetite suppression and other autonomic effects. No government regulatory agency has approved any MT-2-containing product. Documented human harms include a published case report of eruptive atypical nevi and growth of pre-existing nevi in a patient with prior melanoma and dysplastic nevus syndrome (Cardones & Grichnik, 2009), plus other published reports of priapism requiring surgical intervention and rhabdomyolysis associated with self-administered use.
Mechanism of Action
Non-selective agonist across the melanocortin receptor family (MC1R, MC3R, MC4R, MC5R). MC1R activation on melanocytes stimulates eumelanin synthesis (tanning). MC4R activation in the central nervous system drives sexual arousal/erectile activity and contributes to appetite suppression; MC3R/MC5R activation produces additional autonomic effects (cardiovascular tone, exocrine secretion).
For research and educational purposes only. This is not medical advice. Melanotan II is not FDA-approved and carries documented, serious safety risks including melanocytic proliferation in susceptible individuals. Consult a licensed healthcare provider before using any peptide, and see a dermatologist for any new or changing moles.