Your body already makes a hormone that tells your skin to tan. Melanotan 2 is a synthetic peptide engineered to mimic that hormone but in a version that's more potent and longer lasting than PDF) Melanocortin receptor agonists, penile erection, and sexual motivation: Human studies Melanotan II Here's the part nobody explains when they're selling you the "Barbie drug.", , Melanotan 2 is a synthetic peptide that mimics alpha MSH a hormone your body already makes to tell your skin cells to Melanotan What It Is and Its Relation to Skin Cancer