Quick Facts
| Peptide name | PT-141 (Bremelanotide) |
|---|---|
| Research category | Melanocortin Receptor Agonist |
| Molecular formula | C₅₀H₆₈N₁₄O₁₀ |
| Molecular weight | ≈ 1025 g/mol |
| Sequence | Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH |
| Primary research interest | Melanocortin (MC3R/MC4R) signaling and central sexual-arousal research |
| Storage considerations | Lyophilized powder stored frozen at −20 °C; reconstituted solution refrigerated at 2–8 °C and protected from light. |
| Solubility notes | Soluble in sterile or bacteriostatic water; the cyclic structure contributes to its stability in solution. |
| Related compounds | Melanotan II, Oxytocin, Kisspeptin |
Introduction
Research Use Only
PT-141 is discussed here strictly as an investigational research compound for educational and laboratory reference. It is not guidance for human use, diagnosis, treatment, or prevention of disease.
PT-141, also known as bremelanotide, is a synthetic melanocortin receptor agonist studied for its association with central pathways involved in sexual arousal. What makes it distinctive in the research literature is its mechanism: rather than acting on blood vessels the way vasodilator approaches do, PT-141 is studied for effects originating in the central nervous system. It is structurally derived from the melanocortin peptide Melanotan II.
The melanocortin system is an ancient signaling network involved in pigmentation, energy balance, inflammation, and — relevant here — sexual function. PT-141's research interest stems from the observation that activating this system centrally can influence arousal pathways independently of the vascular mechanisms targeted by other approaches.
This profile covers what PT-141 is, its cyclic melanocortin structure, its receptor mechanism, the central-arousal research it appears in, and how it compares with related compounds. Related entries are catalogued in the peptide database.
What is PT-141?
PT-141 is a cyclic seven-amino-acid peptide and the active metabolite of Melanotan II, an earlier melanocortin agonist studied largely for pigmentation. During research on Melanotan II, the arousal-related effects were traced to this metabolite, which was then developed separately as bremelanotide.
Compared with its parent compound, PT-141 lacks the C-terminal amide group, which shifts its activity away from the strong pigmentation effects of Melanotan II and toward the central-arousal pathways that define its research profile. Its cyclic structure contributes to stability and to its affinity for melanocortin receptors.
At a glance
Class: melanocortin receptor agonist. Structure: cyclic 7-residue peptide derived from Melanotan II. Research focus: central (CNS) sexual-arousal pathways via MC4R, distinct from vascular mechanisms.
Molecular and structural characteristics
PT-141 is a cyclic heptapeptide stabilized by a lactam bridge between aspartate and lysine residues. This ring constrains the molecule's conformation, which is studied as a contributor to both its receptor selectivity and its resistance to rapid enzymatic breakdown relative to a linear sequence.
| Property | Value / description |
|---|---|
| Peptide class | Melanocortin receptor agonist |
| Structure | Cyclic heptapeptide (lactam bridge) |
| Origin | Active metabolite of Melanotan II |
| Key distinction | Lacks C-terminal amide of Melanotan II |
| Primary receptor interest | MC4R (with MC3R activity) |
| Molecular weight | ≈ 1025 g/mol |
Mechanism of action
PT-141 acts as an agonist at melanocortin receptors, with the melanocortin-4 receptor (MC4R) the subtype most associated with its arousal-related effects. MC4R is expressed widely in the central nervous system, including hypothalamic regions involved in sexual behavior, energy balance, and autonomic signaling.
The defining mechanistic theme in PT-141 research is that it is a central, neurally mediated agent. Vasoactive approaches to sexual function act peripherally on blood flow; PT-141 is instead studied for initiating signaling within CNS arousal circuits. This distinction is why it is examined in research populations where vascular mechanisms are not the limiting factor.
Because MC4R also participates in appetite and energy regulation, the melanocortin system links PT-141 conceptually to broader metabolic and neuroendocrine research, even though its primary research interest is arousal-related.
- Agonism at melanocortin receptors, notably MC4R.
- Action within central nervous system arousal circuits.
- A neural mechanism, distinct from vascular/blood-flow approaches.
- Shared receptor family with appetite and energy-balance signaling.
Central arousal research applications
PT-141 is studied in research contexts examining central sexual arousal. Early work characterized it as a melanocortin agonist acting on arousal pathways, and subsequent controlled research in female study populations examined subjective arousal and desire endpoints. The recurring theme is a mechanism upstream of the vascular response.
Within the peptide landscape this places PT-141 alongside other neuroendocrine signaling peptides catalogued in the peptide database, and distinguishes it from its pigmentation-focused parent Melanotan II.
Evidence caveat
Findings come from specific research populations and study designs. They are described here as research observations, not as outcomes for any individual.
Comparison: PT-141 vs Melanotan II vs vascular approaches
PT-141 is most directly compared with Melanotan II, the melanocortin peptide it is derived from, and conceptually contrasted with vascular (blood-flow) mechanisms studied for sexual function.
| Approach | Primary target | Mechanism | Note |
|---|---|---|---|
| PT-141 (bremelanotide) | Melanocortin receptors (MC4R) | Central / neural | Active metabolite of Melanotan II |
| Melanotan II | Melanocortin receptors (broad) | Central + strong pigmentation | Parent compound; pigmentation-focused |
| Vascular approaches | Peripheral vasculature | Blood-flow / vasodilation | Different mechanism entirely |
Because PT-141 and Melanotan II share a receptor family but differ in emphasis, they are the natural point of comparison in melanocortin research. Full entries are in the peptide database.
Half-life and pharmacokinetic considerations
PT-141 has a relatively short half-life, on the order of a couple of hours, consistent with its use in research as an on-demand rather than continuously dosed agent. Its cyclic structure contributes to stability in solution but does not extend its duration the way albumin-binding modifications do for incretin peptides.
This short, episodic pharmacokinetic profile is part of why PT-141 research focuses on acute arousal endpoints rather than on sustained exposure, distinguishing it from long-acting peptides studied for chronic metabolic effects.
Reconstitution and handling considerations
Lyophilized PT-141 is reconstituted with sterile or bacteriostatic water, added slowly down the vial wall and swirled gently rather than shaken. The reconstituted solution should be clear; cloudiness or particulates indicate it should be discarded.
Working concentrations are chosen so research volumes are convenient and reproducible. The reconstitution calculator and reconstitution guide describe the general method.
- Add diluent slowly; swirl gently rather than shaking.
- Confirm the solution is clear before use.
- Protect from light and excess warmth.
- Avoid repeated freeze–thaw cycles of reconstituted material.
Storage considerations
Lyophilized PT-141 is most stable frozen at −20 °C, kept dry and away from light. Once reconstituted, it is refrigerated at 2–8 °C and used within a limited window; aliquoting reduces how often a given solution is cycled.
| Form | Condition | Notes |
|---|---|---|
| Lyophilized powder | −20 °C, dark, dry | Most stable for long-term holding |
| Reconstituted solution | 2–8 °C, protected from light | Use within a limited window |
| Freeze–thaw | Avoid repeated cycles | Aliquot to minimize cycling |
Research limitations
PT-141's research base is narrower and more specialized than that of the incretin peptides, and its findings come from specific study populations and designs. Nausea and transient blood-pressure changes are among the effects reported in studies, and melanocortin signaling is broad, so off-target receptor activity is part of the interpretive picture. It is described here strictly for research reference.
- Findings come from specific, specialized research populations.
- Nausea and transient blood-pressure changes are reported in studies.
- Melanocortin agonism is broad; off-target activity is a consideration.
- It is not described here as a therapy, only as a research compound.
Research Use Only
This profile is for educational and laboratory reference. PT-141 is not intended for human consumption, diagnosis, treatment, or prevention of disease.
Frequently Asked Questions
How does PT-141 work?
PT-141 is a melanocortin receptor agonist, acting notably at the MC4 receptor in the central nervous system. It is studied for influencing arousal pathways through a neural mechanism rather than by acting on blood vessels.
How is PT-141 different from Melanotan II?
PT-141 (bremelanotide) is the active metabolite of Melanotan II. It lacks the C-terminal amide of its parent, which shifts its emphasis away from Melanotan II's strong pigmentation effects toward central arousal pathways.
What does it mean that PT-141 is a central mechanism?
Unlike vasodilator approaches that act peripherally on blood flow, PT-141 is studied for initiating signaling within central nervous system circuits involved in arousal — a mechanism upstream of the vascular response.
What receptors does PT-141 target?
It is a melanocortin receptor agonist, with the MC4 receptor most associated with its arousal-related research effects and some MC3 receptor activity. These receptors are part of a broader system that also influences appetite and energy balance.
Why is PT-141 studied as an on-demand compound?
Its half-life is relatively short — on the order of a couple of hours — so research focuses on acute arousal endpoints rather than sustained exposure, unlike long-acting metabolic peptides.
References
- Molinoff PB, et al. PT-141: a melanocortin agonist for the treatment of sexual dysfunction. Ann N Y Acad Sci. 2003.Source
- Diamond LE, et al. An effect of the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist. J Sex Med. 2006.Source
- Kingsberg SA, et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials (RECONNECT). Obstet Gynecol. 2019.Source
Research Use Only
For research use only. Not intended for human consumption, diagnosis, treatment, or prevention of disease. The information on this page is provided for educational and laboratory reference purposes only.