Melanotan 2 (also known as MT-II or MT-2) is an injectable peptide hormone used to promote tanning. MT-2 works by stimulating alpha-melanocyte receptors, which promote the formation of melanin in response to sun exposure. When a substantial amount of MT-II has been taken within recent “memory” of the skin cells, an individual tans as if he were a genetically darker type of Melanotan 2 is typically provided in vials containing 10 mg of lyophilized (freeze-dried) powder. The vials are reconstituted with a convenient amount of bacteriostatic or sterile water, added to the vial by syringe. An example convenient amount of water is 2.5 mL. When this amount of water is used, the resulting solution contains 4 mg of MT-II per mL. If for example wishing to take a dose of 1 mg, a volume of 0.25 mL, or “25 IU” as marked on an insulin syringe, would be taken by injection. An injection may be subcutaneous, intramuscular, or intravenous, according to personal preference. Injection typically is only once per day, but when a person is first trying the drug and judging tolerance, an injection may be divided into two smaller amounts per day.