What PT-141 (Bremelanotide) is

PT-141 (Bremelanotide) belongs to a heterogeneous group of research peptides that modulate central sexual, reproductive, and social-bonding pathways. Unlike GLP-class or regenerative peptides, this group works primarily through neuroendocrine signaling in the hypothalamus and midbrain rather than through peripheral tissue effects.

PT-141 (bremelanotide) is a cyclic heptapeptide melanocortin-4 receptor (MC4R) agonist developed as a derivative of Melanotan-2. It is FDA-approved as Vyleesi for hypoactive sexual desire disorder in premenopausal women.

Mechanism of action

• PT-141 — MC4R agonism in the paraventricular nucleus of the hypothalamus; downstream dopaminergic signaling in the medial preoptic area is the proposed mechanism for the erectogenic and desire endpoints. Unlike PDE-5 inhibitors, PT-141 acts centrally, not on vascular tissue.
• Kisspeptin-10 — binds the GPR54 receptor on GnRH neurons, triggering the pulsatile GnRH release that drives LH and FSH secretion and downstream testosterone or estradiol production.
• Oxytocin — binds the OXTR receptor centrally (paraventricular nucleus, amygdala, nucleus accumbens) and peripherally (uterus, mammary tissue).
• Melanotan-2 — MC1R activation upregulates eumelanin synthesis in melanocytes; MC4R activation drives central sexual arousal signaling.

Published research findings

• PT-141 has FDA-registered Phase 3 data (RECONNECT trials) in hypoactive sexual desire disorder.
• Kisspeptin-10 has published clinical data on LH-pulse induction in both hypothalamic-amenorrhea and healthy-male protocols (Prof. Waljit Dhillo group, Imperial College London).
• Oxytocin has extensive published data across social-cognition, bonding, and autism-adjacent research endpoints.
• Melanotan-2 has decades of pigmentation-research data originating from the University of Arizona program.

Routes reported in research

• Subcutaneous injection dominates for PT-141, Kisspeptin, and Melanotan-2.
• Intranasal delivery is the standard route for oxytocin research protocols due to its CNS accessibility.

Dosing ranges reported in the literature

• PT-141: 0.5–2 mg subcutaneous, dosed acutely 45 minutes to several hours before the desired window.
• Kisspeptin-10: 3–10 µg/kg subcutaneous single-dose in the clinical-research literature.
• Oxytocin (intranasal): 24–40 IU per session in research protocols.
• Melanotan-2: initial titration 250–500 µg subcutaneous daily, then maintenance dosing after reaching desired pigmentation endpoint.

Effects reported in trials

Class-typical reported effects include facial flushing (PT-141, Melanotan-2), transient nausea (PT-141, Melanotan-2, kisspeptin at higher doses), transient blood-pressure change (PT-141), and — with prolonged Melanotan-2 use — darkening of pre-existing nevi that has generated a substantial literature on melanocytic-lesion monitoring.

Standard laboratory handling

Every research vial from PX1 is a lyophilized (freeze-dried) powder sealed under vacuum in a Type-I borosilicate vial with a butyl-rubber stopper and aluminum crimp seal. Correct handling preserves potency and prevents peptide-bond hydrolysis that degrades the active molecule.

• Storage before reconstitution: 2–8 °C refrigerator is ideal; freezer (−20 °C) for storage beyond six months. Short excursions to room temperature during shipping do not compromise integrity — the compound is stable in its solid state.
• Reconstitution solvent: bacteriostatic water for injection (0.9% benzyl alcohol) is standard for research protocols that require multiple sampling events from the same vial. Sterile water is acceptable for single-use protocols.
• Reconstitution technique: inject the diluent slowly against the vial wall — never directly onto the lyophilized cake. Swirl gently; do not shake. Shaking introduces air, denatures peptide secondary structure, and can create insoluble aggregates.
• Post-reconstitution storage: 2–8 °C refrigerated, typically stable 21–30 days depending on the peptide. Freezing a reconstituted solution repeatedly is not recommended — freeze/thaw cycles are the single biggest driver of loss-of-potency in the research literature.
• Concentration math: volume of diluent (mL) = peptide mass (mg) ÷ desired concentration (mg/mL). Example: 10 mg vial + 2 mL bacteriostatic water = 5 mg/mL.

Purity, identity and COA verification

The single most important due-diligence step when sourcing PT-141 (Bremelanotide) for research is reviewing the lot-specific Certificate of Analysis (COA). A credible COA contains:

1. HPLC purity value with chromatogram — target ≥ 98% for injectable-grade research peptides; ≥ 99% for the newest generation of GLP/incretin compounds. A single well-defined main peak with baseline separation from impurities is what you are looking for.
2. Identity confirmation by mass spectrometry — LC-MS or MALDI-TOF confirming the observed molecular weight matches the theoretical mass to within instrument tolerance.
3. Endotoxin (LAL / kinetic-chromogenic) result — expressed in EU/mg; USP guidance for parenteral products is well below 5 EU/kg body-weight equivalent, and reputable suppliers report < 10 EU/mg on the COA.
4. Sterility result — USP <71> membrane filtration or direct inoculation, both bacterial and fungal.
5. Karl Fischer moisture — target < 5% residual water for a properly lyophilized cake.
6. Residual-solvent screen — DMF, TFA, DCM, acetonitrile below ICH Q3C thresholds.

PX1 publishes lot-specific COAs at /purity-reports. If you have received a shipment and want to verify the exact lot documentation for PT-141 (Bremelanotide), cross-reference the lot number on the vial label to the COA PDF.

Why researchers choose PX1 for PT-141 (Bremelanotide)

• 100% U.S. synthesis, lyophilization, and fill/finish. No repackaged imports. Every step from raw amino acid to sealed vial happens under one U.S. GMP-compliant roof.
• Third-party ISO-17025 testing on every lot. Purity, identity, endotoxin, sterility, moisture, and residual-solvent testing performed by an independent analytical laboratory whose data appears on the shipped COA.
• Chain-of-custody documentation from raw material through final QC — the same documentation package a clinical CDMO would provide.
• Same-day shipping on in-stock catalog items ordered before 3 p.m. ET, with insulated packaging and cold-pack where appropriate.

Common researcher questions

Q: How do I know the vial contents match the label? Compare the lot number on the vial to the lot number on the COA. The COA lists HPLC purity, identity by mass-spec, and endotoxin. If any of the three is missing or the lot doesn't match, don't proceed.

Q: Can I use bacteriostatic water past its printed expiration? Bacteriostatic water carries a manufacturer-assigned expiration for the sealed vial. Once punctured, USP guidance limits multi-dose vials to 28 days at 2–8 °C. Beyond 28 days, discard.

Q: Is refrigeration required during shipping? For most lyophilized peptides, no — the solid form is stable at ambient temperature for weeks. Some compounds (IGF-1 LR3, certain GH-releasing peptides) benefit from cold-chain shipping. PX1 uses insulated packaging for temperature-sensitive lines.

Q: What if the reconstituted solution is cloudy? Cloudiness indicates aggregation or precipitation and the solution should not be used. Common causes: over-vigorous shaking, incompatible diluent, or a vial that has passed its stability window.

Research use disclaimer

PT-141 (Bremelanotide) is supplied to licensed research professionals for in vitro and in vivo laboratory research only. Products are not intended for human consumption, veterinary use, diagnostic use, therapeutic use, or as a food additive or cosmetic. Nothing on this page constitutes medical advice. Consult the primary literature — clinical-trial registrations, peer-reviewed publications — before designing any protocol. Compounds discussed here are investigational; several have not received FDA approval for any indication.

Additional PX1 references

• Complete research library
• Lot-specific purity reports
• Product catalog
• Manufacturing & QC standards