Melanotan 2 (MTII)

Melanotan II developed at the University of Arizona is a synthetic analog of the naturally occurring melanocortin peptide hormone alpha-melanocyte stimulating hormone (α-MSH) that in usage has been shown to have melanogenesis (tanning) and aphrodisiac effects in preliminary studies and clinical trials. It is a cyclic lactam analog of α-MSH with the amino acid sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2.

Unlicensed and untested powders sold as "melanotan II" are found on the Internet and are reported to be used by thousands of members of the general public. Multiple regulatory bodies have warned consumers the peptides may be unsafe and ineffective in usage with one regulatory agency warning that consumers who purchase any product labeled "melanotan" risk buying a counterfeit drug.