PT-141 (Bremelanotide)
PT-141 is the arousal peptide, working on brain receptors that drive desire directly rather than on blood flow the way erectile-dysfunction drugs do. It's built for premenopausal women with low sexual desire, and it has become common off-label among men wanting the same lift. A dose is a single self-injection, taken at least 45 minutes ahead of anticipated intimacy rather than daily, and usable up to once a day and eight times a month.
What it does
FDA-approved for low desire
Women with acquired, generalized low sexual desire are the population PT-141 was built and approved for, sold under the name Vyleesi. It's a fixed 1.75 mg self-injection, taken at least 45 minutes before anticipated intimacy, usable up to once a day and eight times a month. It's the only compound in this catalog with a genuine FDA approval behind it, and that approval covers this exact population and this exact dose, nothing broader.
Sources: VYLEESI (bremelanotide injection), 2019
Off-label use in men
A large share of PT-141's real-world use is men taking it off-label for libido and erectile support, often alongside or instead of Melanotan II. That use sits entirely outside the approval: the trials behind Vyleesi studied only premenopausal women with low desire, at one fixed dose and a monthly ceiling. Nothing in that evidence speaks to dose, effect, or safety in men.
Sources: VYLEESI (bremelanotide injection), 2019
What to expect
Most people notice nausea after their first dose or two, the most common thing people report, and it tends to ease as the body adjusts. There's also a temporary rise in blood pressure, peaking two to four hours after injection and settling back down within half a day, which is why uncontrolled hypertension and heart disease keep someone off this compound. Flushing, injection-site irritation, and headache round out the rest of what to expect.
Dosing
Regulatory labelFDA-approved dose, Vyleesi prefilled autoinjector1.75 mg, >=45 min before activity, as needed
| Timeframe | Dosage | Frequency | Note |
|---|---|---|---|
| Single dose | 1.75 mg | >=45 min before activity, as needed | Max 1/24h, 8/month1 |
- No more than one dose within 24 hours and no more than 8 doses per month; discontinue after 8 weeks without reported HSDD improvement. Single-dose, disposable prefilled autoinjector (1.75 mg in 0.3 mL), injected into the abdomen or thigh; no reconstitution or vial-based dosing applies to this approved product.
Unapproved research-vial route (distinct from Vyleesi) – No citable dose
No citable figure. Unapproved research vials of bremelanotide acetate, commonly 10 mg and 20 mg lyophilized vials distinct from Vyleesi, are also sold commercially; no published human dosing data specific to that vial-based route were located, and any such community-practice dose should be treated as unsourced.
Primary structure
Ac*NleDAspHHisFD-PheRArgWTrpKLys
Full research
Evidence tier
Approved drug, human RCT evidence
Bremelanotide is FDA-approved with Phase 3 randomized controlled trial evidence underlying that approval, documented in an official FDA prescribing label, for its specific approved indication of premenopausal, acquired, generalized HSDD. This tier applies only to that indication; off-label uses, including male libido and erectile-dysfunction use, fall entirely outside the RCT evidence base described in the label.
Identity
| Full name | Bremelanotide (developmental code PT-141) |
|---|---|
| Class | Synthetic cyclic heptapeptide melanocortin receptor (MCR) agonist, structurally related to alpha-melanocyte-stimulating hormone and to Melanotan II |
| Brand names | Vyleesi |
| Molecular weight | 1025.2 g/mol |
| Sequence | Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH |
Mechanism of action
Plain language
Bremelanotide activates a family of brain and skin receptors (melanocortin receptors) that Melanotan II also activates, but the FDA label states bremelanotide's own binding is not receptor-selective; the practical distinction from Melanotan II is one of engineered structure, approved fixed dosing, and regulatory oversight, not a clean single-receptor separation.
Technical
Per the FDA label, bremelanotide is a melanocortin receptor agonist with activity across multiple subtypes; the label states the potency order is MC1R greater than MC4R greater than MC3R greater than MC5R greater than MC2R, and that MC1R and MC4R binding are considered most clinically relevant at therapeutic doses. The label states the exact mechanism by which MC receptor agonism improves HSDD symptoms is unknown. Separately, structural biology work on MC4R-agonist complexes has characterized bremelanotide, along with afamelanotide and other agonists, bound to the human MC4R receptor. Some secondary structural sources describe bremelanotide's linear, ring-opened form as having reduced MC1R affinity relative to the cyclic, amidated Melanotan II, which would explain bremelanotide's comparatively lower propensity to cause skin pigmentation changes; this structure-activity claim is consistent with, but not identical to, the FDA label's own potency ranking, and is presented as a secondary-source explanation rather than an FDA-confirmed mechanism.
Sources: VYLEESI (bremelanotide injection), 2019, Structural biology of, 2021, Secondary structural comparison
What it’s used for
Approved
- FDA approved 21 June 2019 (NDA 210557) as VYLEESI, for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD), based on Phase 3 randomized controlled trials referenced in the FDA label. This is the only compound in this catalog with a genuine FDA-approved indication and an official FDA label. Not approved for use in men or in postmenopausal women. EMA status for Vyleesi was not confirmed in this research pass.
Off-label / community use
- Off-label and community use for erectile dysfunction and general libido enhancement in men exists but is not an FDA-reviewed indication and is not supported by the cited label evidence, which is specific to premenopausal HSDD in women. PT-141 is frequently discussed in community sources as interchangeable with Melanotan II for male libido and erectile use; no cited trial evidence supports that extrapolation, and it falls entirely outside the label's studied population, fixed dose, and monthly ceiling.
Pharmacokinetics
| Half-life |
Regulatory label Approximately 2.7 hours (range 1.9-4.0 hours) |
|---|---|
| Tmax |
Regulatory label Approximately 1.0 hour (range 0.5-1.0 hours) |
| Subcutaneous bioavailability |
Regulatory label Approximately 100% |
| Cmax and AUC |
Regulatory label Cmax 72.8 ng/mL; AUC 276 hr*ng/mL |
| Volume of distribution and plasma protein binding |
Regulatory label Volume of distribution 25.0 +/- 5.8 L; plasma protein binding 21% |
| Metabolism and excretion |
Regulatory label Metabolized by peptide hydrolysis of the cyclic amide bonds; excreted 64.8% in urine and 22.8% in feces |
Reconstitution
| Vial strength | 10 mg or 20 mg (unapproved research-vial form of bremelanotide acetate, distinct from the FDA-approved Vyleesi autoinjector) |
|---|---|
| Diluent | Bacteriostatic water |
| Diluent volume | 2 mL |
| Concentration | 5 mg/mL (5,000 mcg/mL) |
Sources: Commercial vendor pages
Dose calculator
Enter a vial strength, diluent volume, and desired dose to see the resulting concentration, dose volume, and units on a standard U-100 insulin syringe. Nothing entered here is saved, stored, or sent anywhere – the calculation runs only in your browser.
This calculator needs JavaScript. The arithmetic it runs is: concentration = vial strength in mg divided by diluent volume in mL; dose volume in mL = dose in mg divided by concentration; units on a U-100 syringe = dose volume in mL times 100.
Storage and post-reconstitution stability
Unopened storage
FDA-approved Vyleesi autoinjector: store at or below 25 degrees C (77 degrees F), do not freeze, protect from light, discard if the solution is cloudy, discolored, or contains visible particles. Unapproved lyophilized research vials: stored frozen or refrigerated, protected from light, per standard peptide handling.
Post-reconstitution stability – Regulatory label
Discard if cloudy, discolored, or contains visible particles; not a numbered shelf-life figure, since Vyleesi ships ready-to-use and requires no reconstitution. Store at or below 25 degrees C (77 degrees F); do not freeze; protect from light
Sources: VYLEESI (bremelanotide injection), 2019
No citable figure. No post-reconstitution stability study or vendor-stated shelf-life figure was located for the separately sold, unapproved research-vial form of bremelanotide acetate.
Safety
Contraindications
- Uncontrolled hypertension; known cardiovascular disease.
Notable risks
- Most common adverse reactions at an incidence of at least 2%: nausea (40% versus 1% placebo), flushing (20.3% versus 0.3%), injection-site reactions (13.2% versus 8.4%), headache (11.3% versus 1.9%), vomiting (4.8% versus 0.2%). Nausea occurs in 40% of patients and tends to improve by the second dose; pretreatment with ondansetron was not effective per the label.
- Documented, label-mandated cardiovascular effect: transient blood pressure elevation, peak increase approximately 6 mmHg systolic and 3 mmHg diastolic at 2-4 hours post-dose, returning to baseline within 12 hours; heart rate reduction of up to 5 beats per minute. No additive cardiovascular effect was observed with repeat daily dosing 24 hours apart in label-cited data.
- Focal hyperpigmentation reported in 1% of patients receiving up to 8 doses per month, involving face, gingiva, and breast, with higher risk in patients with darker skin; the label states resolution after discontinuation was not confirmed in all cases, and advises considering discontinuation if it develops.
- One case of acute hepatitis was reported in label-cited clinical data; causality was not established.
Sources
- Secondary structural comparison sources describing bremelanotide as the ring-opened, des-amide relative of Melanotan II, used for structure-activity framing only; the FDA label is the authoritative source for receptor potency ranking
- VYLEESI (bremelanotide injection) full prescribing information, initial US approval 2019, NDA 210557. FDA/DailyMed. (2019)
- Structural biology of MC4R-agonist complexes including bremelanotide (biorxiv preprint, structural characterization) (2021)
- Commercial vendor pages for unapproved research-grade bremelanotide vials (vial size only, not a clinical source; distinct from FDA-approved Vyleesi)
This is a research and educational reference, not medical advice. Nothing on this site is a recommendation to use any compound.