PT-141 (Bremelanotide)

PT-141, also known by its non-proprietary name bremelanotide, is a synthetic peptide analogue of the endogenous hormone α-Melanocyte-Stimulating Hormone (α-MSH). It was originally developed from Melanotan II as a research compound and has since been approved for a specific therapeutic use.

Its mechanism of action is centered on the central nervous system, where it functions as a non-selective agonist of the melanocortin receptors. Specifically, it is understood to activate the Melanocortin 4 Receptor (MC4R) and Melanocortin 3 Receptor (MC3R) in the brain. Unlike its parent compound, PT-141 has minimal activity at the Melanocortin 1 Receptor (MC1R) and therefore does not produce the skin tanning effect associated with Melanotan I and II. By activating these specific neural pathways, PT-141 modulates brain function related to sexual arousal and desire.

This selective action led to its development as a targeted therapeutic. PT-141, under the brand name Vyleesi, is an FDA-approved medication for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women, administered via subcutaneous injection on an as-needed basis.