Melanocortin

Bremelanotide (PT-141, Vyleesi) is a cyclic seven-amino-acid analog of α-MSH that activates melanocortin receptors in the brain, chiefly MC4R. It is approved in the US for low sexual desire (hypoactive sexual desire disorder) in premenopausal women, based on two phase 3 trials of 1,267 women in which an as-needed 1.75 mg injection modestly increased desire and reduced distress. It was first developed as a nasal spray for erectile dysfunction, where it produced erections in men who did not respond well to sildenafil. Nausea affects about 40% of users.

KPV (lysine-proline-valine) is the last three amino acids of α-melanocyte-stimulating hormone (α-MSH). It keeps the hormone's anti-inflammatory action without its effect on skin pigment. In mice, KPV in the drinking water eased chemically induced colitis, and it cut colitis-associated tumors. It is taken up by PepT1, a peptide transporter that is switched on in the inflamed colon. No human study of KPV has been published.