Melanotan II is a synthetic analogue of the peptide hormone α-melanocyte-stimulating hormone (α-MSH) that stimulates melanogenesis to facilitate tanning.

Melanotan II was found to enhance libido and erections in most male test subjects and sexual arousal with corresponding genital involvement in most female test subjects.

Bremelanotide PT-141 is a synthetic peptide blend that was originally intended to darken skin pigmentation and induce tanning.

During initial testing, patients noted that it caused increased sexual arousal