Bremelanotide (PT-141)
Bremelanotide was developed from the peptide hormone Melanotan II. In initial testing, Melanotan II did induce tanning but additionally caused sexual arousal and spontaneous erections as unexpected side effects in nine out of the ten original male volunteer test subjects (Ref: Uni of Arizona Dr Hunter Wells) Further testing showed Bremelanotide to induce lordosis and was also effective in treating sexual dysfunction in both men (erectile dysfunction or impotence) and women (sexual arousal disorder). Unlike Viagra and other related medications, it does not act upon the vascular system, but directly increases sexual desire via the nervous system.

Melanotan
Melanotan and Melanotan II are both analogs of the peptide hormone alpha-melanocyte stimulating hormone (a-MSH) inducing skin tanning. Like its predecessor, Melanotan I, MT 2 plays a role in stimulating melanogenesis and thus providing a protective mechanism against UV rays since under its actions melanocytes are able to increase production and secretion of hormone melanin. Scientists were also able to notice another characteristic of this compound. MT 2 had a positive effect on libido due to its aphrodisiac properties. Scientists also found MT 2 had a mild positive fat-mobilizing effect.