What Is PT-141 (Bremelanotide)?
PT-141, also known as bremelanotide, is a synthetic research peptide derived from the melanocortin family.
Specifically, PT-141 is a modified analog of α-MSH (alpha-melanocyte-stimulating hormone), a naturally occurring peptide involved in melanocortin receptor signaling.
PT-141 is a heptapeptide that exhibits selective binding affinity for the MC3R and MC4R receptors — both of which are implicated in pathways related to sexual function and arousal in non-clinical models.
Unlike many related peptides, PT-141 does not affect melanogenesis (skin pigmentation), making it of unique interest for researchers investigating the neuroregulation of arousal independent of peripheral effects.
Its primary relevance in laboratory settings is tied to its ability to modulate central melanocortin pathways, making it a subject of ongoing exploration in behavioral, endocrine, and receptor-targeting studies.
Disclaimer: Evolve Peptides only offers the peptide form of PT-141 for research use only. It is not for human or veterinary consumption. PT-141 is not approved for any clinical or therapeutic use. |
PT‑141 Mechanism of Action
PT‑141, or bremelanotide, is a synthetic cyclic heptapeptide designed to activate melanocortin receptors, with high binding affinity for MC3R and MC4R in the central nervous system.
Central Receptor Activation
Upon systemic administration, PT‑141 crosses into brain regions such as the hypothalamus, especially the medial preoptic area (mPOA), where it triggers neuronal activation (confirmed by elevated c‑Fos expression) and stimulates sexual arousal pathways in both animal models and humans.
Specifically, preclinical studies in rats have shown that PT‑141 crosses into the brain and activates neurons within the hypothalamus in the medial preoptic area (mPOA).
Systemic administration triggered significantly increased c‑Fos expression—a marker of neuronal activation—in this region, indicating that PT‑141 directly stimulates hypothalamic neural circuits [1].
Additional research has demonstrated that PT‑141 binds to melanocortin receptors (MC3R and MC4R) densely expressed in the mPOA, which in turn promotes dopamine release, a key neurotransmitter mediating sexual arousal and motivation [1][2].
These studies suggest that PT‑141’s ability to induce sexual behavior and penile erection is driven by central mechanisms—modulating brain areas linked to arousal rather than peripheral vascular pathways.
Central Signaling Cascade & Neurotransmitter Modulation
Once PT‑141 crosses into the brain, it binds primarily to melanocortin-4 receptors (MC4R) in the medial preoptic area (mPOA) of the hypothalamus—a region critical for regulating sexual arousal.
This receptor engagement triggers a signaling cascade that promotes dopamine release, a key neurotransmitter for sexual motivation and reward. Animal studies show that blocking D1-type dopamine receptors in this region significantly blunts the pro-sexual behavioral effects of PT‑141, highlighting dopamine’s essential role in mediating its action [1].
MC3R activation, though less directly tied to arousal, may modulate energy homeostasis, appetite, and dopaminergic tone, potentially explaining off-target effects such as nausea or altered motivation [3].
Together, these mechanisms point to PT‑141’s central action as both behaviorally specific and neurochemically nuanced [4].
Species-Consistent Penile and Arousal Effects
Preclinical studies across rodents and non-human primates consistently show that PT‑141 (bremelanotide) reliably induces penile erections and elevates sexual solicitation behaviors at doses typically between 0.1–1 mg/kg [5].
In human trials of bremelanotide, subcutaneous PT‑141 administered at doses above approximately 1 mg produced dose-dependent erection responses, often within 30 minutes, even without visual sexual cues in both healthy volunteers and men with mild to moderate erectile dysfunction.
Subjects tolerated the drug well, with mainly mild side effects such as flushing and nausea, and no significant cardiovascular events reported at these experimental doses [6].
Central vs Peripheral Mechanism of PT‑141
Unlike phosphodiesterase‑5 inhibitors like sildenafil, which work by relaxing blood vessels in the penis, PT‑141 acts centrally. It targets melanocortin receptors (MC3R/MC4R) in hypothalamic regions—such as the medial preoptic area—triggering neural pathways that initiate arousal and erection via dopamine signaling and brain sexual circuits.
This central mechanism enables sexual response often without direct peripheral vasodilation, distinguishing PT‑141 from vascular-dependent ED treatments [7].
PT‑141 Research Applications
Research into PT‑141 has primarily focused on its role in neuroendocrine regulation, particularly as it relates to sexual behavior, arousal, and mood.
While originally derived as a melanocortin receptor agonist, studies have since explored a variety of potential applications tied to its action in the central nervous system.
Sexual Arousal and Erectile Response
In rodent and non-human primate models, administration of PT‑141 led to increased mating behavior and spontaneous erections—effects attributed to MC4R stimulation in the hypothalamus [8].
In early-phase human studies, PT‑141 demonstrated the ability to induce erections in male subjects without the need for external sexual stimulation. Notably, a Phase 2 clinical trial found that men with mild-to-moderate erectile dysfunction experienced improved erectile function following subcutaneous PT‑141 administration—even in individuals who did not respond to PDE5 inhibitors like sildenafil [6].
These results suggest that PT‑141 may act through distinct pathways compared to conventional treatments.
Female-focused research has also highlighted PT‑141’s potential. In trials involving premenopausal women diagnosed with hypoactive sexual desire disorder (HSDD), PT‑141 was associated with increases in reported sexual desire and satisfaction, along with decreased distress related to low libido [6][9].
These findings led to its eventual development as a pharmaceutical agent (bremelanotide) in clinical contexts, although the peptide compound remains available for research only in the peptide form.
Observations Related to Mood and Emotional Response
Some studies have suggested that melanocortin receptor activation through PT‑141 may have secondary effects on mood and emotional response. In animal models, PT‑141 administration was linked to increased exploratory behavior and markers of reduced anxiety-like behavior [2].
These outcomes may be due to its influence on dopamine and oxytocin signaling, which are also involved in reward, bonding, and emotional regulation.
Though not a primary focus, some human studies have noted subjective reports of elevated mood or increased feelings of connection following PT‑141 administration. However, these effects remain anecdotal and have not been validated as consistent outcomes in formal trials.
Experimental Applications in Metabolic and Neuroregulatory Research
Beyond sexual function, PT‑141’s action at MC3R and MC4R has drawn interest from researchers studying energy balance and appetite regulation.
While these areas are less developed, some rodent studies have indicated that melanocortin agonism may influence feeding behavior and thermoregulation through central pathways.
Analogous melanocortin agonists in rodents—such as MTII and other selective MC4R agonists—have been shown to reduce food intake, promote weight loss, and increase metabolic rate, effects that depend on intact MC4R signaling pathways [10].
In MC4R-deficient mice, these metabolic responses were absent, underscoring receptor specificity [11].
Additionally, melanocortin receptor stimulation can produce biphasic effects on thermogenesis and dopamine-mediated behavior, suggesting modulation of both feeding behavior and reward circuitry.
Early investigation into melanocortin signaling also points toward possible roles in neuroimmune modulation and neuroprotection, though such research remains preliminary and largely in vitro or early animal models [12].
Important: All reported effects are based on controlled laboratory settings. PT‑141 remains a research compound and is not approved for human or veterinary use. Effects observed in research models do not imply safety or efficacy in humans. |
PT‑141 Peptide Characteristics
- Molecular Formula: C50H68N14O10
- CAS Number: 189691-06-3
- Amino Acid Sequence: Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-OH
- Synonyms: Bremelanotide, PT141, MC4R Agonist Peptide
- Molar Mass: 1025.2 g/mol
- Peptide Type: Cyclic heptapeptide, melanocortin receptor agonist
- Solubility: Soluble in sterile water, bacteriostatic water, or dilute acetic acid for research reconstitution
- Stability: Stable in lyophilized form at recommended storage; minimal degradation under cold-chain conditions
- Storage Recommendations:
- Lyophilized powder: Store at -4°F (-20°C) or below for long-term stability
- After reconstitution: Store at 36–46°F (2–8°C) and use within 30 days
- Appearance: White/off-white lyophilized powder
PT‑141 vs Setmelanotide vs PL‑6983
Feature | PT‑141 (Bremelanotide) | Setmelanotide (RM‑493) | PL‑6983 |
Type & Target Receptors | Synthetic cyclic heptapeptide; agonist at MC3R & MC4R, also binds MC1R, MC5R | Cyclic 8‑amino‑acid peptide; selective high‑affinity MC4R agonist (Ki ~2.1 nM, EC₅₀ ~0.27 nM) | Synthetic peptide; selective MC4R agonist developed as a successor to PT‑141 with reduced cardiovascular effects |
Primary Research Focus | Sexual arousal, erectile function, sexual desire in preclinical and early clinical models | Treatment of obesity and hyperphagia due to MC4R pathway deficiencies; energy homeostasis and weight regulation | Female sexual dysfunction and erectile dysfunction; experimental replacement for PT‑141 with improved safety profile |
Mechanism Complexity | Central-mediated activation of MC3R/MC4R driving dopamine release in mPOA; CNS arousal effects | Highly potent activation of MC4R; biased Gq/11 signaling; structural selectivity promotes appetite suppression and weight loss | Modeled for selective MC4R engagement; designed to maintain arousal activity while minimizing blood pressure elevation |
Research Stage | Preclinical and multiple Phase I/II human trials for sexual dysfunction; not FDA-approved in peptide form | EMA and FDA-approved for rare genetic obesity indications (Imcivree) following successful Phase III trials | Still in preclinical or early research stages; development paused due to project prioritization for PT‑141, limited public data |
Observed Research Effects | Dose-dependent enhancement of erections, libido, and arousal in both animal and human models | Significant weight loss and appetite suppression in MC4R-deficient individuals and obese animals; sustained metabolic benefits | Shown in animal studies to deliver arousal-like effects equivalent to PT‑141 but with significantly less vasopressor response |
Dosing & Administration (studies) | Human intranasal or subcutaneous doses from 4–20 mg; systemic onset ~30 min; well tolerated; side effects: flushing, nausea | Daily subcutaneous injections in clinical trials; dosing tailored to body weight and genetic profile (e.g. 1–2 mg needle doses in humans) | Preclinical s.c. administration in animals; precise dose range unpublished; focus on safety differentiation from PT‑141 |
Regulatory / Safety Status | Investigational research compound; not approved for human or veterinary use; known mild side effects in trials | FDA- and EMA-approved drug (Imcivree) for select obesity conditions; safety profile well-characterized in approved populations | Research-use-only peptide; developed to reduce PT‑141’s hypertensive risk; not clinically approved |
Disclaimer | Research use only — not for human or veterinary use; not approved for therapeutic application | Approved therapeutic under brand name Imcivree for certain obesity disorders; not available for research peptide use | Research use only — not for human consumption; not approved for diagnostic or therapeutic use |
PT‑141 Safety and Side Effects in Studies
PT‑141 has been evaluated in both preclinical and human trials (as bremelanotide), primarily for its effects on sexual arousal. While not approved in peptide form for human or veterinary use, data from clinical research has offered insight into its potential safety profile.
In animal models, PT‑141 was generally well tolerated at varying dosages, with studies focusing on behavioral and physiological responses following melanocortin receptor activation. No significant organ toxicity or long-term adverse outcomes were observed in typical short-term dosing studies [11].
PT‑141 may cause a modest, transient elevation in blood pressure and a decrease in heart rate shortly after administration. As a result, clinical trials emphasized caution in individuals with cardiovascular risk [9].
Legal Disclaimer
The PT‑141 peptide product sold by Evolve Peptides is intended strictly for laboratory research use only. It is not approved by the FDA or any other regulatory body for human or veterinary use.
This product is not intended for therapeutic, diagnostic, or cosmetic purposes. It must not be misused, resold, or repackaged for injection, ingestion, or application in or on humans or animals.
Researchers must handle this compound in compliance with all applicable laws and laboratory safety protocols.
Important Note
While bremelanotide is the same active compound found in FDA-approved prescription medications (such as Vyleesi®) for treating female sexual dysfunction, the peptide-grade PT‑141 offered here is not equivalent to or interchangeable with any approved drug product. It has not undergone the pharmaceutical-grade safety testing, dosing validation, or clinical review required for medical use.
Evolve Peptides does not promote or condone the use of any research chemical for unapproved human or animal applications.
Scientific References
- MOLINOFF, P.B., SHADIACK, A.M., EARLE, D., DIAMOND, L.E. and QUON, C.Y. (2003), PT-141: A Melanocortin Agonist for the Treatment of Sexual Dysfunction. Annals of the New York Academy of Sciences, 994: 96-102. https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2003.tb03167.x (paywall)
- King SH, Mayorov AV, Balse-Srinivasan P, Hruby VJ, Vanderah TW, Wessells H. Melanocortin receptors, melanotropic peptides and penile erection. Curr Top Med Chem. 2007;7(11):1098-1106. https://pmc.ncbi.nlm.nih.gov/articles/PMC2694735/ https://www.sciencedirect.com/topics/medicine-and-dentistry/bremelanotide
- Spana C, Jordan R, Fischkoff S. Effect of bremelanotide on body weight of obese women: Data from two phase 1 randomized controlled trials. Diabetes Obes Metab. 2022; 24(6): 1084-1093. https://dom-pubs.pericles-prod.literatumonline.com/doi/10.1111/dom.14672
- Giuliano, F. (2004), Control of Penile Erection by the Melanocortinergic System: Experimental Evidences and Therapeutic Perspectives. Journal of Andrology, 25: 683-691. https://onlinelibrary.wiley.com/doi/full/10.1002/j.1939-4640.2004.tb02842.x
- Rosen RC, Diamond LE, Earle DC, Shadiack AM, Molinoff PB. Evaluation of the safety, pharmacokinetics and pharmacodynamic effects of subcutaneously administered PT-141, a melanocortin receptor agonist, in healthy male subjects and in patients with an inadequate response to Viagra. Int J Impot Res. 2004 Apr;16(2):135-42. https://pubmed.ncbi.nlm.nih.gov/14999221/
- L.E. Diamond, D.C. Earle, W.D. Garcia, C. Spana,Co-administration of low doses of intranasal PT-141, a melanocortin receptor agonist, and sildenafil to men with erectile dysfunction results in an enhanced erectile response, Urology, Volume 65, Issue 4, 2005, Pages 755-759,ISSN 0090-4295. https://www.sciencedirect.com/science/article/abs/pii/S0090429504012725
- Diamond LE, Earle DC, Heiman JR, Rosen RC, Perelman MA, Harning R. An effect on the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist. J Sex Med. 2006 Jul;3(4):628-638. https://pubmed.ncbi.nlm.nih.gov/16839319/
- Kingsberg SA, Clayton AH, Portman D, Williams LA, Krop J, Jordan R, Lucas J, Simon JA. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstet Gynecol. 2019 Nov;134(5):899-908. https://pmc.ncbi.nlm.nih.gov/articles/PMC6819021/
- Girardet C, Butler AA. Neural melanocortin receptors in obesity and related metabolic disorders. Biochim Biophys Acta. 2014 Mar;1842(3):482-94. https://pmc.ncbi.nlm.nih.gov/articles/PMC3819409/
- Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction. Int J Impot Res. 2004 Feb;16(1):51-9. https://pubmed.ncbi.nlm.nih.gov/14963471/
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