Melanotan 2 is a synthetic analog of the naturally occuring melanocortin peptide hormone alpha-melanocyte stimulating hormone (alpha-MSH). Melanotan 2 stimulates the release of alpha-MSH causing melanin production in skin cells. Preliminary studies have shown tanning and aphrodisiac effects. Melanotan 2 is a cyclic lactam analog of alpha-MSH.Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2 (Asp2-Lys7) or Ac-Nle-DHfRWK-NH2 (Asp2-Lys7)