PT-141: research protocol, dosing & reconstitution
Also known as: Bremelanotide, Vyleesi (brand)
Quick answer
What is PT-141?
PT-141 (bremelanotide) is a melanocortin-receptor agonist that acts on desire pathways in the brain rather than on blood flow. It is FDA-approved as Vyleesi for low sexual desire in premenopausal women and is studied for libido in both sexes. Unlike most peptides, it is used situationally rather than on a schedule.
What PT-141 is
PT-141 is a cyclic peptide that emerged from research on Melanotan II, when researchers noticed effects on sexual desire separate from the tanning pathway. It was developed clinically as bremelanotide and approved as Vyleesi (2019) for hypoactive sexual desire disorder in premenopausal women.
In Canada and the US, bremelanotide is a prescription drug. Research vendors sell lyophilizedLyophilizedFreeze-dried. Peptides are shipped as a lyophilized powder ('puck') because the dry form is far more stable than a solution. It must be reconstituted before use in research.See glossary → PT-141 — commonly 10 mg vialsVialThe small sealed glass container peptides are supplied in, topped with a rubber septum that a syringe needle can pass through.See glossary → — as Research Use OnlyRUO (Research Use Only)A regulatory classification meaning a product is sold strictly for laboratory research and is not approved, labeled, or intended for human or veterinary use.See glossary →.
Mechanism of action
PT-141 activates melanocortin receptorsReceptorA protein on or inside a cell that binds specific signaling molecules and triggers a response. Most peptides work by binding particular receptors.See glossary → (primarily MC4R) in the central nervous system, engaging desire and arousal circuits directly in the brain. This central mechanism distinguishes it from PDE5 drugs like sildenafil, which act peripherally on blood flow [1].
Clinical trials (RECONNECT program) reported improvements in desire scores versus placebo in premenopausal women; earlier studies explored erectile response in men.
What researchers study PT-141 for
- Central (brain-mediated) sexual desire pathways
- Melanocortin receptor pharmacology
- Libido research in both sexes
- Non-vascular approaches to sexual dysfunction
What dose of PT-141 do researchers use?
Research literature commonly references doses of ~0.5–2 mg as needed, before activity. This is not a recommendation — the table below summarizes protocols as they appear in published literature and trial designs.
| Context | Dose | Frequency | Duration |
|---|---|---|---|
| Clinical reference (Vyleesi) | 1.75 mg | As needed, ≥45 min before activity | Max 1 dose/24h, 8 doses/month |
| Research literature reference | 0.5–2 mg | As needed, situational | Not cycled |
← Swipe to see the full table
Half-life and dosing timing
Half-life: ~2–3 hours. Route referenced in research: Subcutaneous (research). Half-lifeHalf-lifeHow long it takes for half of a compound to be eliminated from the body. Half-life determines how often researchers dose a compound in protocols.See glossary → is 2–3 hours with effects referenced as lasting considerably longer. Literature references administration 45 minutes to several hours before the research-relevant window. It is situational — no cyclesCycleA defined period of repeated dosing followed by a break, as described in research protocols — for example, 8 weeks on, 4 weeks off.See glossary →, no schedules.
Titration: start low, go slow
Literature strongly references starting at the low end (0.5 mg) — nausea is dose-dependent and the most common reason higher amounts are poorly tolerated.
Skip the PT-141 math
Enter vial size, water volume, and target dose — the free calculator returns concentration, injection volume, and exact U-100 syringe units.
How is PT-141 reconstituted?
| Vial size | BAC water | Concentration | Worked example |
|---|---|---|---|
| 10 mg | 2 mL | 5 mg/mL | 1 mg = 0.2 mL = 20 units on a U-100 syringe |
Add 2 mL of bacteriostatic waterBAC water (bacteriostatic water)Sterile water containing 0.9% benzyl alcohol, which suppresses bacterial growth. It is the standard diluent used to reconstitute lyophilized peptides for multi-dose research vials.See glossary → to a 10 mg vial: 10 ÷ 2 = 5 mg/mL. A 1 mg dose is 1 ÷ 5 = 0.2 mL — 20 units on a U-100 syringeU-100 syringeAn insulin syringe calibrated so that 100 units equal 1 mL. The standard syringe referenced in peptide research; each unit equals 0.01 mL.See glossary →.
New to the process? Read the full step-by-step reconstitution guide.
How long does reconstituted PT-141 last?
Lyophilized: refrigerate. ReconstitutedReconstitutionThe process of mixing a freeze-dried (lyophilized) peptide powder with bacteriostatic water to create a solution of known concentration.See glossary →: refrigerate and use within weeks. Situational use means a reconstituted vial may sit longer — date the vial and discard past the referenced window.
What is PT-141 stacked with in research?
Used situationally on its own. It is not part of cycle-based stacksPeptide stackTwo or more peptides used together in a research protocol because their mechanisms are complementary — for example, BPC-157 with TB-500.See glossary →.
Side effects observed in research
The clinical program's most common effect is nausea (~40% in trials), plus flushing, headache, and transient blood-pressure increases — the reason the label caps frequency. Darkening of skin pigmentation is reported with frequent use (melanocortin lineage).
- Nausea
- Flushing
- Headache
- Transient blood-pressure changes
Frequently asked questions
How is PT-141 different from Viagra?
Sildenafil works peripherally on blood flow; PT-141 works centrally on desire circuits in the brain. They address different parts of the response entirely.
What dose appears in the literature?
The approved clinical dose is 1.75 mg as needed; research literature references 0.5–2 mg situationally. Nausea rises steeply with dose.
Is PT-141 approved in Canada?
Bremelanotide (Vyleesi) is an approved prescription product; research-vendor PT-141 is Research Use Only.
How long before activity is PT-141 referenced?
The clinical label specifies at least 45 minutes before anticipated activity; research reports commonly reference 1–3 hours.
Related research peptides
BPC-157
A synthetic peptide fragment studied for tissue repair, tendon/ligament and gut healing in animal research.
Healing & RecoveryTB-500
A synthetic version of a region of Thymosin Beta-4, studied for cell migration, angiogenesis and tissue repair.
Growth Hormone SecretagogueCJC-1295
A growth-hormone-releasing hormone analog studied for stimulating GH release; often blended with Ipamorelin.
Browse all Sexual Health peptides or start with the beginner’s guide to research peptides.
References
- 1.Kingsberg SA, et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder (RECONNECT trials). Obstet Gynecol. 2019. PubMed ↗