PT-141
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Bremelanotide — melanocortin receptor agonist and the only FDA-approved peptide for central activation of sexual desire.
Quick Facts
| Property | Value |
|---|---|
| Also Known As | Bremelanotide, Vyleesi, BMT |
| Category | Sexual Health |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH (cyclic heptapeptide, metabolite of Melanotan II) |
| Molecular Weight | ~1025.2 Da |
| Molecular Formula | C50H68N14O10 |
| PubChem CID | 9941379 |
| Administration | SubQ (as-needed, not daily) |
| Typical Dose Range | 1.75 mg SubQ (FDA-approved); 1.0-2.0 mg (off-label men) |
| Half-Life | ~2.7 hours |
| Storage | Lyophilized: room temp stable weeks, -20C for 4+ years. Reconstituted: 2-8C, up to 30 days (bacteriostatic water) |
| FDA Status | Approved — Vyleesi (HSDD in premenopausal women, June 2019) |
| WADA Status | Not prohibited |
Mechanism of Action
PT-141 (bremelanotide) is a cyclic melanocortin receptor agonist that acts centrally in the brain to restore sexual desire. It represents a fundamentally different pharmacological approach from PDE5 inhibitors (sildenafil, tadalafil), which act peripherally on vascular smooth muscle to facilitate erections. PT-141 instead targets the motivational and desire pathways upstream of genital arousal (PMID: 33455598).
The peptide crosses the blood-brain barrier and binds primarily to melanocortin-4 receptors (MC4R) in the medial preoptic area (mPOA) and paraventricular nucleus (PVN) of the hypothalamus. MC4R activation in these regions triggers presynaptic dopamine release into mesolimbic reward circuits, generating genuine "appetitive" sexual motivation rather than merely facilitating the mechanical erectile response. This dopaminergic mechanism restores the excitatory tone (dopamine/norepinephrine) relative to serotonergic inhibitory signaling that suppresses sexual desire (PMID: 25096243).
PT-141 also has activity at MC3R, which contributes to metabolic and energy-balance effects. Unlike its parent compound Melanotan II, PT-141 lacks the C-terminal amide that confers MC1R tanning activity, making it more selective for sexual function pathways. However, residual MC1R activity means focal hyperpigmentation remains a dose-dependent risk, particularly with repeated or daily administration.
The onset of action is approximately 45-60 minutes after subcutaneous injection, with effects on desire and arousal lasting 8-12 hours (up to 24 hours in some individuals). Peak plasma concentration occurs at approximately 1 hour post-dose.
Key Research Areas
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Female Hypoactive Sexual Desire Disorder (HSDD): The RECONNECT Phase 3 program (two pivotal trials, N=1247) demonstrated statistically significant improvements in sexual desire (FSDS-DAO score) and satisfying sexual events vs placebo, leading to FDA approval in 2019 (PMID: 31599840).
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Male Erectile Dysfunction: Early Phase 2 data showed efficacy in men with ED, including those who failed PDE5 inhibitors. Safarinejad (2008) demonstrated significant improvements in IIEF scores in a double-blind RCT of 342 men (PMID: 18206919).
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Central Melanocortin Sexual Neurobiology: PT-141 has been instrumental in elucidating the role of the melanocortin system in human sexual behavior, demonstrating that desire and arousal can be pharmacologically separated from genital vascular response (PMID: 25096243).
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PDE5 Inhibitor Non-Responders: Because PT-141 acts centrally rather than peripherally, it represents a therapeutic option for men who do not respond to sildenafil or tadalafil, including those with psychogenic ED or desire-phase dysfunction.
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Combination Therapy: Preclinical and early clinical data suggest synergy between PT-141 (central arousal) and PDE5 inhibitors (peripheral facilitation), with combination use producing greater than 5-fold increases in erectile rigidity duration compared to either agent alone.
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Melanocortin Receptor Pharmacology: PT-141 research has advanced understanding of MC3R/MC4R signaling in hypothalamic circuits governing motivated behavior, with implications beyond sexual health into appetite, energy balance, and social behavior.
Evidence Level Summary
| Evidence Type | Count | Notes |
|---|---|---|
| Human RCTs | 4 | RECONNECT Phase 3 (x2), Safarinejad male ED, dose-finding studies |
| Human observational | 2 | Post-marketing surveillance, real-world use surveys |
| Animal in vivo | 2 | Rodent MC4R-mPOA dopamine release models |
| In vitro | 1 | Melanocortin receptor binding affinity studies |
| Systematic reviews | 1 | Female sexual dysfunction pharmacotherapy review |
Clinical Applications
- Sexual Health — FDA-approved central activator of sexual desire in women; off-label in men
- Erectile Dysfunction — Alternative mechanism for PDE5 inhibitor non-responders
- Libido Enhancement — Restores appetitive sexual motivation via dopaminergic pathways
Protocols Using This Peptide
Ageless Peps Products
- AP-PT141-Vial — PT-141 10mg Vial, SubQ, $48 (WC ID: 771)
- AP-PT141-Capsules — PT-141 Capsules, oral, $480 (WC ID: 799, draft status)
Dosing Reference
Research Dosing Ranges (from literature)
| Route | Dose Range | Frequency | Duration | Source |
|---|---|---|---|---|
| SubQ | 1.75 mg | As-needed, max 1 dose/24h, max 8 doses/month | Ongoing | FDA label (Vyleesi) |
| SubQ | 1.0-2.0 mg | As-needed, 2-3x/week max | Ongoing | PMID: 18206919 (male ED) |
| SubQ | 0.5-1.0 mg (test dose) | Single dose | Initial assessment | Clinical practice |
Cycling
PT-141 is used on-demand, not on a daily cycle. The FDA label specifies a maximum of 8 doses per month to minimize side effects (nausea, hyperpigmentation). No loading phase is required. Tolerance has not been conclusively demonstrated at recommended dosing frequencies, though some practitioners report diminished response with use exceeding 2-3 times per week. A minimum 24-hour washout between doses is mandatory.
Contraindications & Safety
- Contraindications: Uncontrolled hypertension (absolute — transient BP increase of 6-12 mmHg systolic observed in trials); known cardiovascular disease (MI, stroke, unstable angina); concurrent oral naltrexone (reduces naltrexone absorption by ~50%); pregnancy (Category X — suspected reproductive toxicity)
- Common side effects: Nausea (~40%, dose-limiting for many patients), flushing (~20%), headache (~11%), injection site reactions (~5.4%), nasopharyngitis
- Drug interactions: Naltrexone (reduced absorption); caution with antihypertensives (additive BP effects); no significant CYP450 interactions identified
- Pregnancy/nursing: Contraindicated. No adequate human data; animal studies suggest reproductive toxicity
- Special populations: Focal hyperpigmentation risk ~1% at recommended dosing, >30% with daily dosing — often PERMANENT and irreversible. Higher risk in Fitzpatrick IV-VI skin types. Hepatic/renal impairment: no dose adjustment studied but caution advised.
Synergistic Combinations
- Kisspeptin-10 + PT-141 — Kisspeptin drives upstream HPG axis activation (LH/FSH/testosterone) while PT-141 activates central desire pathways; addresses both hormonal and motivational components of sexual dysfunction
- Oxytocin + PT-141 — Oxytocin enhances bonding, intimacy, and orgasm intensity while PT-141 drives desire/arousal; complementary central mechanisms
- PDE5 inhibitors (sildenafil/tadalafil) + PT-141 — Central desire (PT-141) plus peripheral vascular facilitation (PDE5i); synergy demonstrated with >5x increase in erectile rigidity duration
- Melanotan 1 + PT-141 — MT-I provides photoprotective tanning via selective MC1R without the sexual side effects; PT-141 provides targeted MC4R sexual function (safer than using Melanotan II for both)
Related Research
| PMID | Title | Year | Study Type |
|---|---|---|---|
| PMID-31599840 – RECONNECT Phase 3 Bremelanotide for HSDD | Bremelanotide for Hypoactive Sexual Desire Disorder: Results From RECONNECT Phase 3 | 2019 | RCT |
| PMID-18206919 – Bremelanotide for Male Erectile Dysfunction | Evaluation of bremelanotide in the treatment of male erectile dysfunction | 2008 | RCT |
| PMID-33455598 – Melanocortin Agonists in Female Sexual Dysfunction | Melanocortin agonists in female sexual dysfunction | 2021 | Review |
| PMID-25096243 – Melanocortin System in Sexual Function | The melanocortin system and sexual function | 2014 | Review |
| PMID-35076581 – Bremelanotide for Treatment of Female HSDD | Bremelanotide for Treatment of Female Hypoactive Sexual Desire | 2022 | Review |
| PMID-35428435 – Medical Treatment of Female Sexual Dysfunction | Medical Treatment of Female Sexual Dysfunction | 2022 | Review |
| PMID-31893927 – Bremelanotide New Drug Approved for HSDD | Bremelanotide: New Drug Approved for Treating Hypoactive Sexual Desire Disorder | 2020 | Review |
| PMID-36809187 – Small Effects Questionable Outcomes Bremelanotide | Small Effects, Questionable Outcomes: Bremelanotide for Hypoactive Sexual Desire Disorder | 2023 | Narrative Review |
| PMID-31381550 – Bremelanotide Vyleesi for HSDD | Bremelanotide (Vyleesi) for hypoactive sexual desire disorder | 2019 | Review |
| PMID-16681470 – Bremelanotide Phase 2 Male ED | Bremelanotide: an overview of preclinical and clinical data for the treatment of male erectile dysfunction | 2006 | Review |
References
- PMID: 31599840 — Clayton AH, et al. Bremelanotide for female hypoactive sexual desire disorder: RECONNECT Phase 3 trial. Obstet Gynecol. 2019.
- PMID: 18206919 — Safarinejad MR. Evaluation of the safety and efficacy of bremelanotide in male erectile dysfunction. J Sex Med. 2008.
- PMID: 33455598 — Pfaus JG, et al. Melanocortin agonists in female sexual dysfunction. J Sex Med. 2021.
- PMID: 25096243 — Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones. J Pept Sci. 2014.
- PMID: 35076581, 35428435, 31893927, 36809187, 31381550, 16681470.
Related
#peptide #sexual-health #subq