What it is

Melanotan II is a cyclic seven residue melanocortin analogue, built at the University of Arizona by closing a ring between the aspartate and lysine of the alpha-MSH core. It is a broad melanocortin agonist, reaching the pigment receptor on skin cells and the MC3 and MC4 receptors in the brain and spinal cord. It is not the same molecule as Melanotan I, which is linear, thirteen residues long and leans toward pigment alone. PT-141, bremelanotide, is a third relative: an MT-II metabolite developed specifically for sexual desire with the pigment effect left behind.