Category
Sexual Health
Melanocortin receptor agonists and related peptides studied for their effects on sexual function and arousal. PT-141 (bremelanotide) operates centrally rather than through vascular mechanisms, distinguishing this class from phosphodiesterase inhibitors.
6 peptides in this category
How does PT-141 work for sexual dysfunction?
PT-141 (bremelanotide) is a melanocortin receptor agonist that acts on MC3R and MC4R receptors in the hypothalamus to stimulate central arousal pathways. Unlike PDE5 inhibitors that work on penile vasculature, PT-141 modulates the neural circuits governing sexual desire and arousal. It was FDA-approved in 2019 for hypoactive sexual desire disorder (HSDD) in premenopausal women under the brand name Vyleesi, and has been studied in men with erectile dysfunction as a centrally-acting complement to vascular therapies.
Sexual response involves coordinated signaling across central and peripheral nervous systems, and the melanocortin system plays a specific role in initiating sexual arousal at the CNS level. PT-141, also known as bremelanotide, is a cyclic analog of alpha-MSH (alpha-melanocyte-stimulating hormone) that acts on MC3R and MC4R receptors in the hypothalamus. Unlike sildenafil or similar drugs that work by increasing penile blood flow, PT-141 acts upstream — modulating the neural circuits that generate arousal and desire. It was FDA-approved in 2019 under the name Vyleesi for hypoactive sexual desire disorder in premenopausal women, making it one of the few peptides in this entire encyclopedia with a documented regulatory approval pathway.
The broader category of melanocortin peptides includes MT-II (melanotan II), which was investigated earlier for tanning and sexual function but has a less selective receptor profile. Research interest in this area has expanded to include peptides targeting specific receptor subtypes (MC4R selectivity in particular) to separate sexual function effects from the nausea and blood pressure changes that can accompany non-selective melanocortin activation. Understanding the central mechanism makes this category distinct from peripheral vascular or hormonal approaches to sexual dysfunction.
Compounds
Peptides in this category
Gonadorelin
ApprovedGnRH · Gonadotropin-Releasing Hormone
Gonadorelin is a synthetic decapeptide identical to endogenous GnRH. When administered in pulsatile fashion it stimulates LH and FSH release from the pituitary, driving gonadal testosterone and estrogen production. Clinically used for diagnosing hypothalamic-pituitary dysfunction, treating hypogonadotropic hypogonadism, and inducing ovulation. Paradoxically, continuous administration causes receptor downregulation and hormonal suppression — the basis of GnRH agonist therapy in prostate cancer.
Kisspeptin-10
Phase IIKP-10 · metastin 45-54
Kisspeptin-10 is the shortest biologically active fragment of the kisspeptin peptide family, which are potent endogenous activators of the hypothalamic GnRH pulse generator. Research demonstrates it stimulates LH and FSH release and has been studied for infertility, hypogonadotropic hypogonadism, and modulating sexual aversion in psychological studies. It represents a key upstream regulator of the reproductive axis.
Melanotan I
ApprovedAfamelanotide · Scenesse
Melanotan I (afamelanotide) is a linear synthetic α-MSH analog with higher selectivity for MC1R than MT-II. FDA-approved as Scenesse for erythropoietic protoporphyria (EPP), where it reduces phototoxic pain by enhancing melanin production and UV protection. Research explores broader applications in vitiligo, polymorphous light eruption, and other photosensitive disorders.
Melanotan II
PreclinicalMT-II · MT2
Melanotan II is a cyclic synthetic analog of α-MSH that non-selectively activates melanocortin receptors (MC1R–MC5R). It induces skin tanning (via MC1R), erectile function (via MC4R), and sexual arousal while also suppressing appetite. It was the precursor compound from which PT-141 was developed. Research continues despite regulatory concerns due to its broad receptor activity profile.
Oxytocin
ApprovedPitocin · the "bonding hormone"
Oxytocin is a 9-amino-acid neuropeptide produced in the hypothalamus and released by the posterior pituitary. Beyond its classic roles in parturition and lactation, research demonstrates effects on social bonding, trust, empathy, fear extinction, and autism spectrum disorder. Intranasal oxytocin research has produced mixed results in clinical trials, but it remains one of the most studied peptides in social neuroscience.
PT-141
ApprovedBremelanotide · Vyleesi
PT-141 (bremelanotide) is a cyclic heptapeptide melanocortin receptor agonist, FDA-approved for hypoactive sexual desire disorder (HSDD) in premenopausal women. Unlike PDE5 inhibitors, it acts centrally through MC3R and MC4R receptors in the hypothalamus to initiate sexual arousal, making it effective for psychological as well as physiological sexual dysfunction. Research also explores applications in male erectile dysfunction.
Research applications
What researchers are studying
Central arousal pathway activation
PT-141 has been studied in both male and female subjects, with early phase II trials showing increased sexual desire and arousal events compared to placebo in women with HSDD. In men with erectile dysfunction who were non-responsive to sildenafil, PT-141 showed additive effects — suggesting the central melanocortin pathway contributes to arousal independently of penile vascular tone.
Receptor selectivity research
A significant portion of research in this category focuses on separating MC4R-mediated sexual effects from MC1R and MC3R-mediated side effects including nausea and hyperpigmentation. Selective MC4R agonists remain an active area of drug development, using the existing PT-141 data as a proof of concept for central arousal modulation.
Hypoactive sexual desire in women
HSDD is poorly served by existing pharmacology, which is why bremelanotide's approval pathway attracted attention. Clinical data showed statistically significant improvement in satisfying sexual events and desire scores. Unlike flibanserin (the other approved agent), PT-141 is used on-demand rather than daily, which aligns better with how patients actually seek treatment.
Want the full research picture?
Full peptide profiles include mechanism details, study data, dosing research, and sourcing.