PT-141
Central MC3R/MC4R Agonism & Arousal Pathways
Bremelanotide — Melanocortin Receptor Agonist
Last reviewed: August 2026
PT-141 (Bremelanotide) is a synthetic peptide that works through the brain's melanocortin system to influence sexual arousal. Unlike drugs like Viagra or Cialis, which work by increasing blood flow to genital tissue, PT-141 works centrally — in the brain — activating the neural pathways that generate sexual desire itself. It was FDA-approved in 2019 under the brand name Vyleesi® for hypoactive sexual desire disorder (HSDD) in premenopausal women.
PT-141 activates melanocortin receptors (primarily MC3R and MC4R) in the hypothalamus and limbic system — brain regions that regulate motivation, reward, and sexual behavior. This central mechanism produces arousal at the neurological level rather than just the vascular level. In the FDA approval trials, Vyleesi® demonstrated statistically significant improvements in sexual desire and reductions in distress related to low desire compared to placebo.
The distinction between a central (brain-based) and peripheral (blood flow-based) mechanism for sexual function is clinically significant. Many cases of sexual dysfunction, particularly in women, involve desire and arousal at the psychological/neurological level rather than purely vascular issues. PT-141's FDA approval for HSDD validates the melanocortin pathway as a legitimate therapeutic target for sexual health.
PT-141 is FDA-approved as Vyleesi® for female sexual desire disorder, giving it one of the strongest clinical validation profiles in this catalog. Its central mechanism — working through the brain rather than blood vessels — distinguishes it from conventional sexual health drugs. The research-grade peptide supplied by Purgo Labs is for laboratory use only.
What is PT-141?
PT-141, clinically known as bremelanotide, is a synthetic cyclic heptapeptide melanocortin receptor agonist derived from Melanotan II. It is FDA-approved under the brand name Vyleesi® for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women, making it one of the few peptides in this catalog with full regulatory approval and extensive human clinical data.
Unlike phosphodiesterase-5 (PDE5) inhibitors such as sildenafil, which act peripherally on vascular smooth muscle, PT-141 acts centrally through melanocortin receptors in the brain — specifically MC3R and MC4R in the hypothalamus and limbic system. This central mechanism of action represents a fundamentally different approach to sexual dysfunction research.
- PT-141 (Bremelanotide) is a cyclic heptapeptide melanocortin receptor agonist — the same compound FDA-approved as Vyleesi® (2019) for hypoactive sexual desire disorder (HSDD) in premenopausal women.
- Activates MC3R and MC4R in the central nervous system, particularly in the hypothalamus and limbic system, producing pro-sexual effects through a CNS pathway distinct from PDE5 inhibitors (sildenafil, tadalafil).
- Unlike PDE5 inhibitors which act peripherally on vascular smooth muscle, PT-141 acts centrally — it can produce sexual arousal in the absence of direct genital stimulation, and works in both men and women.
- The FDA approval of bremelanotide (Vyleesi®) provides robust clinical validation: Phase 3 trials showed statistically significant improvements in desire and reductions in distress in women with HSDD.
- Research applications include studying the central melanocortin system's role in sexual motivation, the MC4R pathway in reward and arousal, and potential applications in male sexual dysfunction.
Molecular Composition
PT-141 (bremelanotide) has the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, differing from Melanotan II (MT2) by a single modification: the C-terminal amide group of MT2 is replaced by a free carboxylic acid (OH) in PT-141. This modification reduces the compound's melanogenic activity (reducing tanning side effects) while preserving its central melanocortin receptor agonism.
The molecular weight is 1,025.2 Daltons. The cyclic structure, formed by a lactam bridge between aspartate and lysine, confers metabolic stability and enhanced receptor binding affinity.
How Does It Work?
PT-141 increases sexual desire by activating melanocortin receptors in the hypothalamus, enhancing dopaminergic signaling in the brain's reward and arousal circuits.
PT-141 exerts its primary effects through agonism at MC3R and MC4R in the central nervous system, particularly in the hypothalamus, limbic system, and spinal cord. MC4R activation in the medial preoptic area (MPOA) of the hypothalamus — a region critical for sexual motivation and behavior — increases dopaminergic neurotransmission in the mesolimbic pathway, enhancing sexual desire and arousal.
Unlike PDE5 inhibitors, which require sexual stimulation to be effective and act primarily on penile/clitoral blood flow, PT-141 modulates the central neural circuits that generate sexual desire. This distinction is clinically significant: PT-141 can increase sexual motivation in the absence of external stimulation, addressing the desire component of sexual dysfunction rather than the performance component.
Key Research Pathways
MC4R / Hypothalamic Sexual Motivation
MC4R activation in the medial preoptic area (MPOA) increases dopaminergic signaling in the mesolimbic pathway, enhancing sexual desire.
MC3R / Limbic System Modulation
MC3R agonism in limbic structures contributes to arousal and emotional components of sexual motivation.
Dopaminergic Mesolimbic Pathway
Central melanocortin activation increases dopamine release in the nucleus accumbens and ventral tegmental area, the reward circuitry of sexual motivation.
Spinal MC4R / Erectile Signaling
MC4R activation in the spinal cord stimulates nitric oxide-mediated pro-erectile signaling, contributing to peripheral arousal responses.
Key Findings from the Literature
- FDA-approved (Vyleesi®) for hypoactive sexual desire disorder (HSDD) in premenopausal women
- Central mechanism: MC3R/MC4R agonism in hypothalamus — distinct from peripheral PDE5 inhibitors
- Increases dopaminergic neurotransmission in mesolimbic pathway, enhancing sexual desire
- Effective in both male and female sexual dysfunction models (Diamond et al., 2006)
- Cyclic structure derived from MT2 with C-terminal modification reducing melanogenic activity
- Activates MC4R in medial preoptic area (MPOA) — critical region for sexual motivation
Evidence by Claimed Outcome
Each outcome rated by the highest level of evidence available. Tiers follow our 5-tier methodology.
Study counts reflect peer-reviewed publications in the evidence database below. "Theoretical" outcomes have mechanistic rationale only. Learn about our evidence tiers →
Structured Evidence Table
2 cited studies — model, sample size, outcome, and effect size from published literature.
| Study | Model | Sample | Outcome | Effect Size | Level |
|---|---|---|---|---|---|
Diamond LE, et al. (2004) Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic prope… PubMed | Human — Phase II RCT | n=20 | Significant increase in erectile response vs. placebo; centrally mediated | Significant improvement in erectile function scores (p<0.05) | Phase II |
Clayton AH, et al. (2016) Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women PubMed | Human — Phase III RCT (HSDD) | n=1267 | Significant improvement in satisfying sexual events and desire in women with HSDD | SSE increase: +0.7 vs. +0.2 placebo (p<0.001); FDA approved 2019 | Phase III |
Important Research Context
Research References
Peer-reviewed literature supporting the research profile of PT-141
The following peer-reviewed studies form the primary evidence base for PT-141's research profile. All references are sourced from PubMed, NCBI, and peer-reviewed scientific journals. Published research is available through PubMed, NCBI, and peer-reviewed biomedical journals.
- 1.
Diamond LE, et al. A 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. International Journal of Impotence Research. 2004.PMID: 14963471
PT-141 demonstrated pro-erectile effects via central melanocortin receptor activation in controlled clinical evaluation.
- 2.
Safarinejad MR, Hosseini SY. Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study. Journal of Urology. 2008.PMID: 18206919
PT-141 (bremelanotide) improved sexual arousal and desire in women with hypoactive sexual desire disorder.
- 3.
Clayton AH, et al. Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women. Women's Health (London). 2016.PMID: 27181790
Phase III data supporting bremelanotide (PT-141) approval for HSDD in premenopausal women.
PT-141
Sexual Health Research
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Technical Specifications
| Peptide Class | Cyclic heptapeptide melanocortin agonist |
| Molecular Weight | 1,025.2 Da |
| FDA Approval | Vyleesi® — HSDD in premenopausal women |
| Receptor Targets | MC3R, MC4R (central nervous system) |
| Mechanism Type | Central (hypothalamic) — vs. peripheral PDE5 inhibitors |
| Available Sizes | 10mg vials |
| Form | Lyophilized powder |
| Purity | ≥99% (third-party tested) |
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Other Compounds in This Guide
Supporting Research
PT-141 (bremelanotide) is FDA-approved as Vyleesi® (2019) for hypoactive sexual desire disorder (HSDD) in premenopausal women. This is one of the strongest clinical validation profiles in this catalog. The approval is specifically for HSDD in premenopausal women; off-label use in men or for other indications is not supported by the pivotal trial data.
References
- Clayton AH, et al.HUMAN RCT, Phase 3Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women. Women's Health (London). 2016. PubMedPhase III data supporting bremelanotide (PT-141) approval for HSDD in premenopausal women.
- Kingsberg SA, et al.HUMAN RCT, Phase 3Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstetrics & Gynecology. 2019. PubMedTwo Phase 3 RCTs confirmed significant improvement in satisfying sexual events and desire scores vs placebo.
Research Databases
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