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 PDF) Melanotan Tanning Injection: A Rare Cause of Priapism Melanotan Erectile Dysfunction: What the Early Research Shows and Practical Considerations 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