PT-141

PT-141, now known by its generic name bremelanotide, is a synthetic cyclic heptapeptide that acts as an agonist of melanocortin receptors, primarily MC3R and MC4R. Unlike phosphodiesterase inhibitors such as sildenafil (Viagra) that work through vascular mechanisms, PT-141 acts centrally in the brain on the melanocortin system to influence sexual arousal and desire. This unique mechanism of action makes it the first medication to target sexual desire through central nervous system pathways.

PT-141 was originally derived from the tanning peptide Melanotan II during research at the University of Arizona. Researchers noticed that Melanotan II produced spontaneous erections in male subjects, leading to the development of PT-141 as a more targeted compound for sexual dysfunction. The peptide was refined to reduce the skin-darkening effects of Melanotan II while preserving the pro-sexual properties.

The FDA approved bremelanotide (marketed as Vyleesi) in June 2019 for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. Clinical trials demonstrated that bremelanotide significantly increased sexual desire and decreased distress related to low sexual desire compared to placebo. In the RECONNECT phase 3 trials, approximately 25% of women treated with bremelanotide experienced a clinically meaningful increase in sexual desire, compared to about 17% on placebo.

While approved only for women with HSDD, PT-141 has generated considerable interest for broader applications in sexual dysfunction for both men and women. Early clinical research showed efficacy in men with erectile dysfunction, including some who did not respond to sildenafil. The peptide continues to be researched and used off-label in various clinical settings for both male and female sexual health concerns.