PT-141

PT-141 (Bremelanotide) is a cyclic heptapeptide melanocortin receptor agonist with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, derived from the synthetic peptide Melanotan II through targeted structural modifications. Unlike phosphodiesterase inhibitors that act peripherally on blood vessels, PT-141 activates melanocortin-4 receptors (MC4R) in the central nervous system, specifically in the hypothalamus and limbic system, to modulate sexual arousal and desire through dopaminergic and oxytocinergic pathways. In 2019, the FDA approved Bremelanotide (marketed as Vyleesi) for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women, making it the first melanocortin-based therapeutic approved for sexual dysfunction. Clinical trials demonstrated statistically significant improvements in sexual desire and reduction in distress associated with low desire. The melanocortin system targeted by PT-141 is involved in a broad range of physiological processes beyond sexual function, including appetite regulation, inflammation, energy homeostasis, and pigmentation. Common side effects in clinical trials included nausea, flushing, and transient increases in blood pressure.