Bremelanotide, developed under the code name PT-141, is a synthetic peptide that switches on melanocortin receptors in the brain and skin. It is a close structural relative of Melanotan II, the 1980s “tanning peptide,” and was developed by Palatin Technologies first for erectile dysfunction and then for low sexual desire in women.
Unlike Melanotan II, bremelanotide is an approved medicine. The FDA approved it on June 21, 2019 as Vyleesi, a 1.75 mg autoinjector for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). It is not approved for men or to enhance sexual performance. In the pivotal trials the gains in desire were small, 40% of women had nausea, and blood pressure rose briefly after each dose.
This page summarizes what the FDA label, the clinical trials and published reviews report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Class | Synthetic cyclic peptide (7 amino acids); non-selective melanocortin receptor agonist |
| Relation to other peptides | Analog of Melanotan II; same ring structure except for one end group |
| Brand / approval | Vyleesi; FDA approved June 21, 2019 (NDA 210557, new molecular entity); now marketed by Cosette Pharmaceuticals |
| Approved use | Acquired, generalized HSDD in premenopausal women only |
| Route and strength | Subcutaneous injection, 1.75 mg/0.3 mL single-dose autoinjector |
| Labeled dose | 1.75 mg as needed, at least 45 minutes before sexual activity; no more than 1 dose in 24 hours; more than 8 doses a month not recommended |
| Half-life (label) | ≈2.7 h (range 1.9–4.0 h) after a subcutaneous dose |
| Key risks | Transient blood pressure rise, nausea (40%), focal skin darkening |
| US status | Prescription only; the label lists no controlled-substance schedule |
| WADA 2026 | Not named on the Prohibited List |
What it is
Structure
The Vyleesi label describes bremelanotide as a synthetic, cyclic heptapeptide (a ring-shaped chain of seven amino acids). Its starting amino group is capped with an acetyl group, and its other end is a free carboxylic acid. One of its building blocks is the mirror-image D-form of phenylalanine, a change that helps resist breakdown by enzymes. The drug is supplied as the acetate salt; the label gives the molecular weight as 1025.2 (free base) (Vyleesi label).
Relation to Melanotan II
The University of Arizona group that created the melanotans describes PT-141 as “a new MTII analog” taken forward by Palatin Technologies (Hadley and Dorr, Peptides 2006). PubChem’s entries show how close the two are: the ring and all side chains are identical, and the only difference is the end of the chain.
| Feature | Melanotan II | Bremelanotide (PT-141) |
|---|---|---|
| End group | Carboxamide | Free carboxylic acid |
| Formula (PubChem) | C₅₀H₆₉N₁₅O₉ | C₅₀H₆₈N₁₄O₁₀ |
| Molecular weight (PubChem) | 1024.2 g/mol | 1025.2 g/mol |
| Development aim | Tanning, then erectile dysfunction | Erectile dysfunction, then low desire in women |
| Approval status | Never approved | FDA approved (Vyleesi), 2019 |
| Human pharmacokinetics | No published human data | Characterized in the FDA label |
Sources: PubChem CID 92432 and PubChem CID 9941379.
Bremelanotide is often called a “metabolite” of Melanotan II online. The structures are consistent with that idea, since losing the amide group of MT-II would leave bremelanotide. However, we found no published human study showing that MT-II is actually converted to bremelanotide in the body, so this page describes it as an analog. The Melanotan I page covers the linear, full-length analog used for skin pigmentation.
How it works
Bremelanotide activates several melanocortin receptors. The label lists its potency order as MC1R, then MC4R, MC3R, MC5R and MC2R, and states that MC1R and MC4R binding matter most at therapeutic doses (Vyleesi label):
- MC4R is found on nerve cells in many brain areas. The label states that the way bremelanotide improves HSDD “is unknown.”
- MC1R sits on melanocytes (pigment cells). Activating it increases melanin, which explains the skin darkening seen with frequent dosing.
A review by trial investigators and company authors proposes, based mainly on animal studies, that bremelanotide acts on MC4R in the medial preoptic area of the hypothalamus and increases dopamine release there (Pfaus et al., CNS Spectr 2022). This is a hypothesis, not a demonstrated mechanism in women.
Unlike sildenafil or tadalafil, which act on blood vessels in the genitals, bremelanotide acts mainly in the central nervous system. See Viagra (sildenafil) and Cialis (tadalafil) for comparison.
Pharmacokinetics
From the Vyleesi label, after a single 1.75 mg subcutaneous dose (Vyleesi label):
| Parameter | Value |
|---|---|
| Bioavailability (subcutaneous) | About 100% |
| Time to peak (median) | ≈1.0 h (range 0.5–1.0 h) |
| Peak level (mean Cmax) | 72.8 ng/mL |
| Total exposure (mean AUC) | 276 h·ng/mL |
| Volume of distribution | 25.0 ± 5.8 L |
| Protein binding | 21% |
| Terminal half-life | ≈2.7 h (range 1.9–4.0 h) |
| Clearance | 6.5 ± 1.0 L/h |
| Metabolism | Breakdown of the peptide (amide) bonds |
| Excretion of radiolabel | 64.8% in urine, 22.8% in feces |
A few other points from the label:
- Blood levels rise less than proportionally with dose between 0.3 and 10 mg, and peak levels plateau at 7.5 mg.
- Injecting into the abdomen or thigh gives similar exposure.
- Exposure is 1.2-, 1.5- and 2-fold higher in mild, moderate and severe kidney impairment, and 1.2- and 1.7-fold higher in mild and moderate liver impairment.
An earlier intranasal formulation, tested in healthy men, had a median time to peak of 0.5 h and a mean half-life of 1.85–2.09 h (Diamond et al., Int J Impot Res 2004).
Approved medical use
Indication
Vyleesi is approved for premenopausal women with acquired, generalized HSDD: low sexual desire that causes marked distress or relationship difficulty, and that is not due to another medical or psychiatric condition, relationship problems, or a medication. “Acquired” means it developed after a period of normal desire; “generalized” means it occurs regardless of situation or partner (Vyleesi label).
The label lists two limitations of use: it is not indicated for HSDD in postmenopausal women or in men, and it is not indicated to enhance sexual performance.
Labeled dosing
| Item | Label wording (summarized) |
|---|---|
| Dose | 1.75 mg subcutaneously in the abdomen or thigh, as needed |
| Timing | At least 45 minutes before anticipated sexual activity |
| Frequency limits | No more than one dose in 24 hours; more than 8 doses per month not recommended |
| When to stop | After 8 weeks if the patient reports no improvement |
| Product | Single-dose prefilled autoinjector, 1.75 mg/0.3 mL |
The label explains the limits: few trial patients used more than 8 doses a month, and more frequent dosing raises the risk of skin darkening and lengthens the time each month when blood pressure is raised.
Development and approval
Palatin sponsored the phase 3 trials and licensed North American rights to AMAG Pharmaceuticals, which submitted the application to the FDA (Dhillon and Keam, Drugs 2019). FDA approved it on June 21, 2019 under a standard review as a new molecular entity (Drugs@FDA). The current label is held by Cosette Pharmaceuticals.
What the research shows
Phase 3 trials in women (RECONNECT)
Two identical 24-week, randomized, double-blind, placebo-controlled trials enrolled 1,267 premenopausal women with HSDD (mean age 39). Participants self-injected 1.75 mg or placebo as needed, and most used it 2–3 times a month (Kingsberg et al., Obstet Gynecol 2019; Vyleesi label).
The two co-primary outcomes were the desire score of the Female Sexual Function Index (FSFI, a 1.2–6.0 scale where higher means more desire) and a single question on how often the woman felt bothered by low desire (FSDS-DAO item 13, a 0–4 scale where lower means less distress). Results from the label:
| Outcome | Study 1: bremelanotide | Study 1: placebo | Study 2: bremelanotide | Study 2: placebo |
|---|---|---|---|---|
| Women analyzed (desire score) | 313 | 315 | 282 | 288 |
| Desire score, mean baseline | 2.1 | 2.0 | 2.0 | 2.1 |
| Desire score, mean change | +0.5 | +0.2 | +0.6 | +0.2 |
| Distress item, mean change | −0.7 | −0.4 | −0.7 | −0.4 |
| Satisfying sexual events, mean change | 0.0 | −0.1 | 0.0 | 0.0 |
Both studies met both co-primary outcomes (desire: p = 0.0002 and p under 0.0001; distress: p under 0.0001 and p = 0.0053). The placebo-adjusted improvement in the desire score was 0.30 and 0.42 points in the two trials (0.35 pooled), and the reduction in distress was 0.37 and 0.29 points.
The number of satisfying sexual events, a secondary outcome, did not differ from placebo in either trial (p = 0.76 and p = 0.70). Many more women dropped out of the 24-week phase on bremelanotide: 40% vs 13% in Study 1 and 39% vs 25% in Study 2.
Long-term extension
Women who finished the core trials could enter a 52-week open-label extension in which everyone received bremelanotide. Of 856 eligible women, 684 joined and 272 completed it (Simon et al., Obstet Gynecol 2019). In women who had taken bremelanotide during the core phase, desire scores rose by 1.25–1.30 points from the original baseline. The study had no control group, all analyses were descriptive, and most participants left before the end, so these figures likely overstate the typical effect.
Phase 2b dose-finding trial
A 12-week trial randomized 397 premenopausal women with sexual desire or arousal disorders to placebo or 0.75, 1.25 or 1.75 mg as needed (Clayton et al., Womens Health 2016). Pooled 1.25 and 1.75 mg results against placebo:
| Outcome | Bremelanotide 1.25/1.75 mg | Placebo | p |
|---|---|---|---|
| Satisfying sexual events per month | +0.7 | +0.2 | 0.018 |
| FSFI total score | +3.6 | +1.9 | 0.0017 |
| FSDS-DAO total distress score | −11.1 | −6.8 | 0.0014 |
This trial is the basis for the 1.75 mg dose. Unlike phase 3, it found a small gain in satisfying sexual events.
How big is the benefit?
Independent reviewers have questioned how meaningful the phase 3 effects are:
- A reanalysis using FDA application data found results similar to the published ones. It also found that stopping because of side effects was far more likely on bremelanotide (OR 11.98, 95% CI 3.74–38.37; one extra dropout for every 6 women treated), and it concluded the drug is “generally not useful” (Spielmans, J Sex Res 2021). The trial investigators published a rebuttal disputing the analysis (Kingsberg et al., J Sex Res 2021).
- A follow-up analysis reported that 8 of 11 efficacy outcomes registered on ClinicalTrials.gov had not been published, and that effects on them ranged from nil to small (Spielmans and Ellefson, J Sex Res 2024).
- An independent expert review judged the drug moderately safe and well tolerated but its overall clinical benefit “modest” (Cipriani et al., Expert Opin Pharmacother 2023).
- A 2026 meta-analysis of treatments for female desire, arousal and orgasm disorders found that bremelanotide improved FSFI total, desire and arousal scores and reduced distress (Toledo et al., J Minim Invasive Gynecol 2026).
Erectile dysfunction in men (not approved)
Interest in melanocortin drugs for sexual function began when Melanotan II was found to cause erections in several species, including humans (Shadiack et al., Curr Top Med Chem 2007). PT-141 was therefore first studied in men. All of the following were small, short company-sponsored studies that measured erections with RigiScan (a device that records penile rigidity):
| Study | Design and participants | Main finding |
|---|---|---|
| Diamond et al., Int J Impot Res 2004 | Intranasal; healthy men and men with ED who responded to Viagra | Significant erections vs placebo at doses above 7 mg, onset ≈30 min; flushing and nausea most common |
| Rosen et al., Int J Impot Res 2004 | Subcutaneous 0.3–10 mg in healthy men; 4 or 6 mg vs placebo crossover in men with an inadequate response to Viagra | Significant erections above 1.0 mg in healthy men and at both doses in men with ED |
| Diamond et al., Urology 2005 | 19 men with ED; crossover of intranasal PT-141 plus low-dose sildenafil vs sildenafil alone | Combination gave a greater erectile response than sildenafil alone |
The only larger trial in men, a 342-man study of intranasal bremelanotide from a single Iranian center, is now under an editorial expression of concern (Safarinejad and Hosseini, J Urol 2008). The same author’s bremelanotide trial in women was retracted after he did not provide his original data (Safarinejad, J Sex Med 2008). We do not rely on either result.
The intranasal program did not lead to approval. When the company moved to subcutaneous injection for women, the phase 2b trial added intensive blood pressure monitoring “to address US FDA concerns expressed after earlier studies of an intranasal BMT formulation” (Clayton et al., Womens Health 2016). The FDA label states that Vyleesi is not indicated for men.
Appetite and body weight (early studies)
Because MC4R also regulates appetite, Palatin ran two small phase 1 trials in premenopausal women with obesity (Spana et al., Diabetes Obes Metab 2022). In one, subcutaneous bremelanotide three times daily for 15 days reduced body weight more than placebo (difference −1.3 kg, 95% CI −1.9 to −0.8) and cut intake by about 400 kcal/day. These regimens were far more frequent than the labeled maximum, and they are not an approved use.
Side effects and risks
Vyleesi has no boxed warning. Its label lists three warnings: transient blood pressure rise, focal hyperpigmentation and nausea (Vyleesi label).
Blood pressure and heart rate
Each dose briefly raises blood pressure and slows the heart:
- In clinical studies, systolic pressure rose by up to 6 mmHg and diastolic by up to 3 mmHg, peaking 2–4 hours after the dose. Heart rate fell by up to 5 beats per minute.
- Values usually returned to baseline within 12 hours.
- In a 127-woman ambulatory monitoring study with once-daily dosing for 8 days, mean daytime systolic pressure rose by 1.9 mmHg (95% CI 1.0–2.7) and diastolic by 1.7 mmHg (95% CI 0.9–2.4).
A separate randomized trial with 24-hour monitoring in 397 women found systolic increases of 3.1–3.2 mmHg over placebo with 1.75 mg in the first 4 hours after dosing, with heart rate falling by 4.6–4.7 bpm (White et al., J Hypertens 2017).
For this reason the label contraindicates Vyleesi in uncontrolled hypertension or known cardiovascular disease, and does not recommend it for people at high cardiovascular risk. Taking doses closer together than 24 hours may add to the blood pressure effect.
Nausea and other common effects
Adverse reactions in at least 2% of women in the phase 3 trials and more common than with placebo (label Table 1):
| Reaction | Bremelanotide (n = 627) | Placebo (n = 620) |
|---|---|---|
| Nausea | 40.0% | 1.3% |
| Flushing | 20.3% | 0.3% |
| Injection site reactions | 13.2% | 8.4% |
| Headache | 11.3% | 1.9% |
| Vomiting | 4.8% | 0.2% |
| Cough | 3.3% | 1.3% |
| Fatigue | 3.2% | 0.5% |
| Hot flush | 2.7% | 0.2% |
| Tingling (paresthesia) | 2.6% | 0.0% |
| Dizziness | 2.2% | 0.5% |
| Nasal congestion | 2.1% | 0.5% |
Further detail from the label:
- Nausea usually began within an hour of a dose and lasted about two hours. It was most frequent after the first dose (21% of women) and fell to about 3% with later doses. 13% of women used anti-nausea medicine, and 8% left the trials because of nausea.
- Ondansetron did not help. Taking 8 mg ondansetron 30 minutes before a dose did not reduce nausea in a 228-woman study, and the label does not recommend this.
- Discontinuation for any adverse reaction was 18% on bremelanotide vs 2% on placebo. Serious adverse reactions occurred in 1.1% vs 0.5%.
Focal hyperpigmentation
Because bremelanotide activates MC1R on pigment cells, it can darken patches of skin. In phase 3, 1% of women using up to 8 doses a month developed focal darkening, including on the face, gums and breasts, compared with none on placebo. In another study, 38% of women developed it after 8 daily doses, and 14% more developed new changes over 8 further days. Women with darker skin were more affected, and the darkening did not clear in all women after stopping (Vyleesi label).
Melanotan II, which also strongly activates MC1R, has been linked in case reports to new and darkening moles; those reports are summarized on the Melanotan II page. We found no comparable published reports for bremelanotide in the sources reviewed here.
Liver
During the open-label extension, one woman developed acute hepatitis after 10 doses over a year, with liver enzymes over 40 times the upper limit of normal. Tests normalized 4 months after stopping. No other cause was found, so the label states that a role for bremelanotide “could not definitively be excluded,” while noting no overall liver signal across the program.
Interactions
From the label and a review of the full development program (Clayton et al., J Womens Health 2022):
- Slower stomach emptying. Bremelanotide may delay absorption of oral drugs. The label advises avoiding it with oral drugs that need a threshold level to work, such as antibiotics.
- Naltrexone. It may markedly lower blood levels of oral naltrexone, so the label advises against combining it with naltrexone products used for alcohol or opioid addiction.
- Indomethacin. Its levels were also lowered; the label suggests considering stopping bremelanotide if a fast-acting pain reliever works too slowly.
- Alcohol. In a 24-person crossover study using a 20 mg intranasal dose, alcohol did not change bremelanotide levels. Headache was more frequent than with bremelanotide alone.
Pregnancy
Few pregnancies occurred in the trials. In animal studies, bremelanotide given to pregnant dogs at exposures about 16 times the human dose increased embryo loss, and mice exposed in pregnancy had offspring with developmental delays at about 125 times human exposure. A no-effect dose was not identified in either species. The label advises effective contraception and stopping the drug if pregnancy is suspected.
Who should not use it
- People with uncontrolled high blood pressure or known cardiovascular disease (contraindicated).
- People at high cardiovascular risk (not recommended).
- Men, postmenopausal women and children: not approved, and safety and effectiveness are not established in pediatric or geriatric patients.
- People with severe kidney or liver impairment: use with caution, as side effects such as nausea and vomiting may be more frequent and severe.
Legal status and use outside medicine
- United States. Bremelanotide is a prescription drug approved only as the Vyleesi autoinjector (Drugs@FDA). Products sold online as “PT-141” vials or nasal sprays are not the FDA-approved product.
- Sport. The 2026 WADA Prohibited List does not name bremelanotide or other melanocortin agonists. Its S0 class covers substances with no current approval for human use, a definition that does not fit a drug holding FDA approval (WADA 2026 Prohibited List).
- Illicit market. An Italian forensic lab identified Melanotan II and bremelanotide in eight unlabeled samples seized by police together with anabolic steroids, hormone modulators, sexual enhancers and stimulants intended for the bodybuilding black market (Mestria et al., Drug Test Anal 2021). The contents and purity of such products cannot be known from their labels.
Key takeaways
- A Melanotan II analog that became an approved drug. Bremelanotide differs from MT-II only at one end of the peptide chain, but unlike MT-II it went through phase 3 trials and was FDA approved in 2019.
- Approved for one narrow use. Vyleesi is approved only for acquired, generalized HSDD in premenopausal women, at 1.75 mg as needed, with no more than one dose a day and no more than 8 a month recommended.
- Short-acting. Its half-life is about 2.7 hours, with peak levels about an hour after injection.
- Modest benefit. Desire scores improved by 0.30–0.42 points over placebo on a 1.2–6.0 scale, satisfying sexual events did not increase, and independent reanalyses call the effect small.
- Side effects are common. 40% had nausea and 20% flushing, 18% stopped because of side effects, and every dose briefly raises blood pressure.
- Not approved for men. Early erection studies in men were small, and the largest trial in men is under an expression of concern.
Sources
- Cosette Pharmaceuticals. Vyleesi (bremelanotide injection) prescribing information, revised March 2024. DailyMed.
- Food and Drug Administration. Drugs@FDA: Vyleesi (bremelanotide acetate), NDA 210557, original approval June 21, 2019. Drugs@FDA.
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- World Anti-Doping Agency. The 2026 Prohibited List. In effect January 1, 2026. WADA 2026 Prohibited List.
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