PT-141
Bremelanotide · Vyleesi (brand)
PT-141, generically bremelanotide, is unusual here in holding a genuine FDA approval, for hypoactive sexual desire disorder in premenopausal women, taken as needed rather than daily. It reached that approval through a phase 3 programme, which places it in a small group on this site alongside the GLP-1 compounds and tesamorelin.
Its mechanism is what makes it interesting relative to the drugs most people compare it to. PDE5 inhibitors work on blood vessels; PT-141 acts on melanocortin receptors in the central nervous system, upstream of that. It is a desire mechanism rather than a plumbing one. That is why it was studied in women and why it is discussed for situations where vascular drugs do not help.
It derives from the same peptide family as melanotan II, and it shares that compound's side effect profile in miniature. Nausea and flushing are the common ones, and blood pressure changes are why its labelling is specific about cardiovascular history.
How it works
PT-141 activates melanocortin receptors, principally MC4R, in regions of the brain involved in sexual arousal. That is upstream of the vascular effects PDE5 inhibitors produce. Which is why the two are not interchangeable and why PT-141 was studied for desire rather than for erectile function specifically.
MC1R activity, at the receptor involved in pigmentation, is weak enough that tanning is not a meaningful effect at approved doses. Its relative melanotan II is a different story.
Blood pressure rises transiently after dosing and returns to baseline within hours. That is a documented, dose-related effect, not an anecdote, and it is why the approved product limits how often it can be used.
Regulatory status — United States
Approved by the FDA as a prescription medicine for hypoactive sexual desire disorder in premenopausal women. It is not approved for use in men, and material sold as a research chemical is not the approved product.
Last reviewed 12 Aug 2026. Regulatory positions in this category change frequently; we date this line so you can see how current it is.
What it is studied for
Each entry states the evidence behind it. We do not rank indications by effectiveness — for most compounds here, that would be a claim nobody can support.
Hypoactive sexual desire disorder
Clinical trialThe approved indication, in premenopausal women.
EvidenceTwo randomised, double-blind, placebo-controlled phase 3 trials.
Sexual function in men
Community practiceWidely discussed, and outside the approval.
EvidenceEarlier-phase studies exist in men, but development for that indication was not completed and it is not approved.
Identity and clearance
Molecule
- Class
- Cyclic heptapeptide, melanocortin receptor agonist
- Molecular weight
- 1025.2 Da
- Length
- 7 amino acids
Sequence
Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH
A cyclic analogue of alpha-MSH, structurally close to melanotan II but with different receptor selectivity.
Pharmacokinetics
Clinical trialTaken as needed rather than on a schedule, which is what the short half-life allows.
Dose protocols reported in sources
Displayed for reference only. Every row says where it came from, and a trial protocol and a community convention are not the same kind of information. None of this is fed into the calculator, and none of it is a recommendation.
| Goal | Dose | Frequency | Route | Units, 5 mg vial | Source | Start this protocol |
|---|---|---|---|---|---|---|
| Approved regimen for the licensed indication | 1.75 mg | As needed, no more than once in 24 hours and 8 times a month | SubcutaneousTaken about 45 minutes before anticipated activity. The frequency cap is part of the approved labelling, not a convention. | 35 u | Clinical trial | Start this |
Start this copies a row into a protocol of your own, which you can then edit. Where a source gave a dose range or an ambiguous frequency, those fields arrive empty — we will not pick a number on your behalf.
Calculator
Work out what to draw
Pre-filled with a 10 mg vial as a worked example. These are not recommended values — change them to match the vial in front of you.
Draw to 35 units on a 1 mL U-100 syringe. That is 0.35 mL, containing 1.75 mg of PT-141.
Check35 units falls between the printed lines on a 1 mL U-100 syringe. Mixing with 1.6 mL of water instead would put this dose at 28 units.
Bioalmanac performs arithmetic on values you enter. It does not recommend doses, schedules or compounds, and nothing here is medical advice. Confirm every calculation against your vial and syringe before drawing, and speak with a licensed healthcare provider.
Open this calculation in the full calculator
Units, concentration, bacteriostatic water — the glossary defines the vocabulary, and a unit is not a fixed volume.
Safety
Reported effects
- NauseaClinical trial
Very common in trials
The most frequently reported effect, and the most common reason people stopped in the trials.
- FlushingClinical trial
Common in trials
- HeadacheClinical trial
Common in trials
- Transient rise in blood pressure with a fall in heart rateClinical trial
Documented in trials
Peaks in the hours after dosing and resolves. It is the reason the approved labelling restricts use in uncontrolled hypertension and cardiovascular disease.
- Darkening of the skin or gumsClinical trial
Uncommon, more likely with frequent use
A melanocortin effect. More associated with repeated dosing than single use.
When to stop
- Chest pain, severe headache or visual disturbance after dosing. These can accompany a marked blood pressure rise. Seek urgent care.
- Any allergic response: rash, hives, facial swelling or difficulty breathing. Seek urgent care.
- Persistent nausea or vomiting that does not settle within hours.
- New or spreading darkening of skin, gums or moles.
- An erection lasting more than four hours is a medical emergency. Seek immediate care.
Interactions and situations that need care
- Uncontrolled hypertension or known cardiovascular diseaseAvoid
Transient blood pressure elevation after dosing is a documented, dose-related effect measured in the trials. In someone with uncontrolled hypertension or existing cardiovascular disease that is a real cardiac risk, and the approved labelling excludes them.
- Pregnancy and breastfeedingAvoid
Not recommended; there is no benefit to weigh against unknown fetal risk.
- Existing melanoma or many atypical molesUse caution
Melanocortin receptor activity affects pigment cells. Repeated stimulation of that pathway in someone with a melanoma history or heavy mole burden is an unquantified risk, and skin should be monitored by a dermatologist.
- NaltrexoneUse caution
The approved labelling notes reduced naltrexone exposure when taken together, which matters if naltrexone is being used for alcohol or opioid dependence.
What to expect
- In the phase 3 trials the effect on desire was statistically significant and modest in size. It is not a dramatic result, and the trials say so.
- Nausea was the most common reason participants discontinued, and it is dose-related.
- It works on desire rather than on blood flow, so it is not a substitute for, or equivalent to, a PDE5 inhibitor.
- The approval is for premenopausal women. Use in men is common in gray-market channels and is not what the evidence covers.
Storage and handling
- Freeze-dried powder
- Refrigerated at 2–8 °C, protected from light.
- After mixing
- Refrigerated at 2–8 °C. Do not freeze once mixed.
- Long-term, frozen
- Unopened powder is stable at −20 °C or colder.
With other peptides
- Melanotan IIcaution
Both act on melanocortin receptors. Combining them stacks the same receptor family, compounding nausea, blood pressure effects and pigmentation changes.
- Afamelanotidecaution
The same receptor family with different selectivity: PT-141 favours MC4R, afamelanotide MC1R. Running both means stimulating the whole family. This is what melanotan II already does and is not obviously desirable.
Checking your vial
Research chemicals carry no manufacturing standard, so what the vial looks like is often the only quality signal available before you use it. More on assessing quality and COAs.
White cake, clear solution
Standard for a short cyclic peptide.
Collapsed cake or cloudy solution
Indicates heat damage or degradation.
Questions
- How is PT-141 different from a PDE5 inhibitor?
- PDE5 inhibitors act on blood vessels to affect blood flow. PT-141 acts on melanocortin receptors in the brain — upstream of that — affecting desire, not the vascular response. They are not interchangeable and were studied for different things.
- Is it approved for men?
- No. The FDA approval is for hypoactive sexual desire disorder in premenopausal women. Earlier-phase work in men exists but that development was not completed.
- Why is there a limit on how often it can be used?
- The approved labelling caps it at once in 24 hours and eight times a month, largely because of the transient blood pressure rise that follows each dose.
References
Bremelanotide for hypoactive sexual desire disorder: RECONNECT phase 3 trials
Obstetrics & Gynecology, 2019 · Two randomised, double-blind, placebo-controlled phase 3 trials
Premenopausal women with hypoactive sexual desire disorder · n = 1247 · 1.75 mg subcutaneous, as needed · 24 weeks
Statistically significant but modest improvement in desire and reduction in associated distress. Nausea, flushing and headache were the most common adverse events, and nausea was the leading cause of discontinuation.
10.1097/AOG.0000000000003500
Commonly reported community protocols
Bioalmanac editorial summary of public community sources, 2026 · Not a study
Records that PT-141 is widely used off-label in men. Carries no evidential weight about safety or effect in that population.
Related compounds
Melanotan II
A melanocortin agonist that darkens skin by stimulating melanin production. Carries the most serious dermatological concern of anything on this site.
Afamelanotide
The approved member of the melanotan family. Same idea as melanotan II, taken through a full regulatory process, and the contrast between them is instructive.
Ipamorelin
A selective growth hormone secretagogue that prompts a short pulse of GH release. Widely used, and supported almost entirely by early pharmacology rather than outcome trials.
CJC-1295
A GHRH analogue that raises growth hormone by amplifying the body's own release signal. Sold in two forms whose durations differ by two orders of magnitude.
Next
What to do with PT-141
- Keep a record of itTurn a dose and a schedule into a protocol, then log what you actually take. PT-141 is filled in for you.
- See what it costsPer-milligram prices read from vendor sites and confirmed by a person, so vial sizes compare.
- Check a combinationWhat our profiles record about PT-141 alongside each other compound — including the pairs where nothing is recorded.
Keep this page honest
If something here is wrong, out of date, or missing a source, tell us and we will fix it and say that we did.
This page is educational. It describes what published research reports, not what you should do. Peptides discussed here are largely not approved for human use, and nothing on Bioalmanac is medical advice. No clinician reviews these pages.
Page last updated 12 Aug 2026