RESEARCH MONOGRAPH · KDC-MN-091

PT-141 (Bremelanotide)

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

72/100

MC4 receptor agonist with real FDA approval for sexual dysfunction and an interesting central-nervous-system mechanism story

PT-141 (bremelanotide, Vyleesi) is the cyclic heptapeptide melanocortin receptor agonist developed by Palatin Technologies, originally derived from Melanotan II by removing the alpha-amidation and modifying the lactam bridge. It received FDA approval in 2019 for hypoactive sexual desire disorder in premenopausal women, making it one of the few peptides with a defined clinical sexual-function indication.

What we like is the central mechanism. PT-141 acts at MC4R in the paraventricular nucleus of the hypothalamus to drive pro-erectile and pro-libido neural circuits independent of vascular mechanisms. Unlike PDE5 inhibitors (sildenafil, tadalafil) which work peripherally on smooth muscle relaxation, PT-141 works on the central regulatory circuit, which means it's effective in subjects who don't respond to peripheral vasodilators. The clinical data is reasonably solid: RECONNECT trials in women showed reproducible improvements on validated sexual function scales, and male erectile dysfunction trials showed similar effect signatures.

What we dont like: the tolerability profile is rougher than the marketing suggests. Nausea is common (about 40% incidence in the approval trials), transient hypertension and flushing are real and dose-related, and hyperpigmentation can occur with repeated use because of MC1R cross-reactivity (though much less than Melanotan II). The pricing of the approved product is also genuinely steep for what amounts to an as-needed indication.

Sourcing is mostly fine for research-grade. The cyclic heptapeptide synthesis is well-established (it's a smaller, simpler molecule than its parent Melanotan II), and reputable peptide vendors produce HPLC pure material at gram scale. The cyclization is the main quality-control concern; verify mass spec to confirm the lactam bridge is intact. Cheap vendors sometimes sell linear precursor as cyclized peptide.

For research on MC4 receptor pharmacology and central sexual-function neural circuits, PT-141 is the cleanest available tool compound and the only FDA-approved one. The MC4R selectivity is better than Melanotan II (less MC1R activation, less pigmentation), and the human evidence base is meaningful. Worth respect, and the central-mechanism story is the underappreciated angle that distinguishes it from peripheral ED drugs.

Evidence: 80
Mechanism: 82
Reliability: 72
Safety: 65
Sourcing: 75
Value: 60
Signal: 72
Staying power: 65

Plain-language summary Intrigue 72 / 100

PT-141 (bremelanotide), sold as Vyleesi, is a synthetic peptide approved by the FDA for hypoactive sexual desire disorder in premenopausal women. It activates melanocortin receptors in the brain that regulate sexual response. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Melanocortin-4 receptor agonist

A FDA-approved (2019) melanocortin receptor agonist (Vyleesi) for hypoactive sexual desire disorder in premenopausal women, derived from melanotan II.

Abstract

Bremelanotide (Vyleesi; PT-141; CAS 189691-06-3; molecular formula C50H68N14O10; molecular weight 1025.18) is a cyclic heptapeptide melanocortin receptor agonist approved by the FDA in 2019 for hypoactive sexual desire disorder (HSDD) in premenopausal women. The compound is derived from the alpha-MSH analog melanotan II by structural modification that increased selectivity toward MC4 versus MC1 (reducing the skin pigmentation activity prominent in melanotan II). PT-141 was originally developed as a sunless tanning agent before pivoting to sexual function applications when central effects were observed. Mechanism is melanocortin-4 receptor agonism in the central nervous system, with downstream effects on dopaminergic and oxytocinergic pathways implicated in sexual response. Reported research dose ranges in the literature are around 1.75 mg subcutaneous. Pharmacokinetics: plasma half-life approximately 2.7 hours; the central effect persists 4 to 6 hours after administration. Adverse events include nausea (highest frequency), hyperpigmentation with chronic use, and modest blood pressure elevation.

Mechanism of action

Selective MC4 melanocortin receptor agonist; downstream dopaminergic and oxytocinergic effects.

Reported research dose ranges

1.75 mg SC (reported research dose ranges in the literature).

References

Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder. Obstet Gynecol 2019.

Read the full monograph

The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, reported research dose ranges, sourcing and quality verification, reconstitution and handling, stack interaction considerations, and a curated reference list. Available as a research-use-only PDF download.

KDC-MN-091

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

Download PDF →

FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

Kodiac sells research compounds for investigative use only.

PT-141 (Bremelanotide)

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

Quick actions

Categories

Help and policies

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

Adjacent monographs