Warning issued over increased use of 'Barbie drug' 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 Melanotan II Uncovered Your Essential Guide to Tanning, Libido Enhancement, and Smart Peptide Protocols: Proven Methods to Inject Safely, Monitor An FDA Reversal on Peptides Could Open the Market to Unsafe Drugs ProPublica Emerging Threat: Melanotan, Repackaging, and Online Sales