PT-141 (bremelanotide): benefits, evidence and legal status

PT-141, now called bremelanotide, is a synthetic cyclic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone (α-MSH) that the FDA approved on June 21, 2019 as Vyleesi, for one narrow use: acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women.

Its strongest evidence is two phase 3 randomized controlled trials (RECONNECT) in 1,267 women, which found statistically significant gains over placebo in desire scores (0.35 points on a 1.2–6 scale) and in distress about low desire [Human RCT, n=1,267] (Kingsberg 2019). The approved label also shows the limits: no difference from placebo in the number of satisfying sexual events, nausea in 40% of users, and a transient rise in blood pressure after every dose (Vyleesi label). Products sold online as “PT-141” are not Vyleesi; in August 2026 the FDA named one seller’s “PT-141” as an unapproved new drug.

Item	Status
US FDA status	Approved as Vyleesi (NDA 210557, June 21, 2019), prescription only, for acquired, generalized HSDD in premenopausal women; not for men, postmenopausal women or sexual performance (label)
Compounding (503A/503B)	Not on FDA’s Category 1 or 2 lists; as a component of an FDA-approved drug it meets one 503A bulk-substance criterion (FDA 503A); “research use” PT-141 was named as an unapproved new drug in an August 2026 FDA warning letter
WADA 2026	Not named in the 2026 or 2027 Prohibited List; S0 covers only substances without any regulatory approval (WADA 2026 List)
Strongest evidence	Approved label; Human RCT (two phase 3 trials, n=1,267)
Human trials	10 records on ClinicalTrials.gov, incl. NCT02333071 and NCT02338960
EU	No marketing authorization in EMA’s medicines data (EMA)
Last checked	2026-10-06

Identity

Property	Value
Names	Bremelanotide; PT-141; Vyleesi (brand)
Sequence	Ac-Nle-cyclo-(Asp-His-D-Phe-Arg-Trp-Lys-OH), a cyclic heptapeptide (label)
Molecular formula	C50H68N14O10 (free base)
Molecular weight	1025.2 g/mol (free base)
CAS	189691-06-3 (PubChem CID 9941379)
Half-life	About 2.7 hours after subcutaneous use (range 1.9–4.0) (label)
Routes studied	Subcutaneous (approved); intranasal (earlier trials)
Class	Melanocortin receptor agonist

What is PT-141 (bremelanotide)?

PT-141 was the development code used by Palatin Technologies, whose scientists described it in 2003 as a synthetic α-MSH analogue that acts at the MC3R and MC4R melanocortin receptors and caused erections in rats and nonhuman primates [Animal] (Molinoff 2003). Early human work tested it for erectile dysfunction, first as a nasal spray. Development then turned to women. Palatin sponsored the phase 3 trials and licensed North American rights to AMAG Pharmaceuticals, which filed the New Drug Application (Dhillon 2019). The FDA approved it in 2019 as a new molecular entity; the application is now held by Cosette Pharmaceuticals (Drugs@FDA).

How does PT-141 work?

• Receptor binding: bremelanotide activates melanocortin receptors nonselectively, in the order MC1R, MC4R, MC3R, MC5R, MC2R; at therapeutic doses MC1R and MC4R matter most [Approved label] (Vyleesi label).
• Brain desire circuits: in female rats it increased solicitation behavior without changing lordosis or pacing [Animal] (Pfaus 2004), and the effect followed infusion into the medial preoptic area of the hypothalamus but not the ventromedial hypothalamus [Animal] (Pfaus 2007). A review proposes dopamine release in that area as the link [review of animal data] (Pfaus 2022).
• Not a reward-circuit drug: in female Syrian hamsters it did not enhance sexual reward, and the authors concluded it does not act on the ventral tegmental area–nucleus accumbens reward pathway [Animal] (Borland 2025).
• Human brain imaging: in 31 women with HSDD, a single dose raised self-rated desire for up to 24 hours and changed brain responses to erotic images on functional MRI [Human RCT, crossover, n=31] (Thurston 2022).
• Skin pigment: MC1R sits on melanocytes, and activating it increases pigmentation, which explains the hyperpigmentation side effect [Approved label].

Despite this work, the label itself says the mechanism by which the drug improves HSDD is unknown.

What the research shows

Claim	Evidence level	Best study and result
Raises sexual desire in premenopausal women with HSDD	Human RCT (n=1,267)	Kingsberg 2019: FSFI desire +0.35 vs placebo (integrated, scale 1.2–6)
Reduces distress about low desire	Human RCT (n=1,267)	Kingsberg 2019: FSDS-DAO item 13 −0.33 vs placebo (scale 0–4)
Increases satisfying sexual events	Human RCT: not shown in phase 3	Label: no significant difference (p=0.76; p=0.70)
Benefit persists over a year	Human, open-label (n=684)	Simon 2019: improvements sustained; 272 completed, no control group
Improves arousal scores	Systematic review and meta-analysis	Toledo 2026: improved FSFI total, desire and arousal
Treats erectile dysfunction	Human RCT, small; key trial under expression of concern	Rosen 2004: erectile response at 4 and 6 mg; not approved
Reduces body weight	Human phase 1 RCT (short)	Spana 2022: −1.3 kg vs placebo over 16 days
Acts through brain MC4R	Animal; Human RCT (imaging, n=31)	Thurston 2022: desire up for up to 24 h; fMRI changes
Enhances sexual reward	Animal: not shown	Borland 2025: no effect in hamsters

Low sexual desire in women

The RECONNECT program ran two identical 24-week trials from 2015 to 2016. Women injected 1.75 mg or placebo as needed; 96.6% of participants were enrolled at US sites and their mean age was 39. Both trials met their two primary endpoints, with desire gains of 0.30 and 0.42 points over placebo and distress reductions of 0.37 and 0.29 points [Human RCT, n=1,267] (Kingsberg 2019). The FDA label reports mean desire-score changes of 0.5 and 0.6 on bremelanotide against 0.2 on placebo, and a mean distress change of −0.7 against −0.4 in both studies (Vyleesi label). Dropout was uneven: 40% versus 13% (Study 1) and 39% versus 25% (Study 2) left the double-blind period early. Prespecified subgroup analyses found benefits across age, weight and testosterone groups, with few exceptions [Human RCT, n=1,202] (Simon 2022).

The dispute over effect size

An independent reanalysis found that 72.72% of the protocol-listed outcomes were not reported in the main paper, that adverse-event dropout was far higher on the drug (odds ratio 11.98) and that participants were more likely to complete the trial and continue into the extension on placebo (Spielmans 2021). The trial authors published a rebuttal titled “Failure of a Meta-analysis” (Kingsberg 2021). A second analysis reported that 8 of 11 registered efficacy outcomes had gone unpublished and that their effect sizes ranged from nil to small (Spielmans 2024). A drug bulletin review concluded that bremelanotide produced no additional enjoyable sexual experiences in trials and called for the approval to be reconsidered (Mintzes 2021).

Men and erectile dysfunction

In healthy men, subcutaneous doses above 1.0 mg produced erections measured by RigiScan, and men with a poor response to sildenafil responded at 4 and 6 mg [Human, small controlled studies] (Rosen 2004). A nasal form worked at doses above 7 mg, with the first erection after about 30 minutes (Diamond 2004), and a low nasal dose added to 25 mg sildenafil beat sildenafil alone in 19 men (Diamond 2005). The largest male trial (342 men) now carries a journal expression of concern (J Urol 2023). The label states that Vyleesi is not indicated in men.

Weight and other uses

Because MC4R also controls appetite, Palatin tested bremelanotide in obese premenopausal women: over 16 days, weight fell 1.3 kg more than on placebo and intake fell by about 400 kcal a day [Human phase 1 RCT, n=30 on drug in Study A] (Spana 2022). Those trials used several doses a day, far beyond the approved pattern, and were run by the company. A combination trial with tirzepatide and a small diabetic kidney disease study are registered, without published results so far.

Human studies and trials

A search of ClinicalTrials.gov on October 3, 2026 returned 10 registered bremelanotide studies. The sponsor’s safety review counted 3,500 subjects in 43 completed studies across phases 1 to 3 (Clayton 2022).

Trial	Phase, n, status	Population and result
NCT00425256	Phase 2; completed 2007	Women with arousal disorder; no results posted
NCT01382719	Phase 2b; efficacy n=327; completed 2012	Premenopausal women; pooled 1.25/1.75 mg improved satisfying events (+0.7 vs +0.2/month) (Clayton 2016)
NCT02333071	Phase 3; n=723; completed 2017	RECONNECT 301; met both primary endpoints
NCT02338960	Phase 3; n=714; completed 2017	RECONNECT 302; met both primary endpoints
NCT03973047	Phase 1; n=228; completed 2019	Healthy women; ondansetron did not reduce nausea
NCT04179734	Phase 4; n=40; completed 2020	HSDD brain imaging; desire up for up to 24 h (Thurston 2022)
NCT04943068	Phase 3; n=193; completed 2023	Bridging trial (Kwang Dong); no results posted
NCT05709444	Phase 2; n=16; completed 2024	Diabetic kidney disease; no results posted
NCT06565611	Phase 2; n=108; active, not recruiting	With tirzepatide for obesity; no results posted
NCT06867835	Phase 4; n=10; completed 2025	Breast-milk levels in lactating women; no results posted

Two other published studies need caution. A 2008 trial in women with arousal disorder was retracted after its author did not supply the original data (retraction notice), and a 2008 trial in 342 men with erectile dysfunction is under an expression of concern (Safarinejad 2008). An early crossover study in 18 women with arousal disorder found more reports of moderate or high desire after a single nasal dose, but no significant change in measured vaginal blood flow (Diamond 2006).

Doses used in studies

The amounts below are given for scientific context only and are not recommendations.

Route and amount	Population	Study
Subcutaneous, 1.75 mg as needed	Premenopausal women with HSDD (phase 3)	Kingsberg 2019
Subcutaneous, 0.75, 1.25 or 1.75 mg	Premenopausal women (phase 2b)	Clayton 2016
Subcutaneous, 0.3–10 mg single doses	Healthy men	Rosen 2004
Intranasal, 20 mg single dose	Women with arousal disorder	Diamond 2006
Intranasal, 20 mg with or without alcohol	24 healthy adults	Clayton 2017
Subcutaneous, 2.5 mg and 2.0 mg daily pairs	Obese women (phase 1)	Spana 2022

The approved label dose is 1.75 mg by subcutaneous autoinjector at least 45 minutes before anticipated sexual activity, with no more than one dose in 24 hours and more than 8 doses a month not recommended; the label also says to stop after 8 weeks if there is no improvement (Vyleesi label). No established human dose exists outside approved labels.

Side effects and safety

The label’s adverse-reaction table compares 627 women on bremelanotide with 620 on placebo in the phase 3 trials [Approved label] (Vyleesi label).

Adverse reaction	Bremelanotide vs placebo
Nausea	40.0% vs 1.3%
Flushing	20.3% vs 0.3%
Injection site reactions	13.2% vs 8.4%
Headache	11.3% vs 1.9%
Vomiting	4.8% vs 0.2%
Stopped due to adverse reactions	18% vs 2%

• Nausea: 21% had it after the first dose and about 3% after later doses; it began within an hour and lasted about two hours; 13% needed anti-nausea medicine, and 8% left the trials because of it. Ondansetron taken beforehand did not prevent it in 228 healthy women [Approved label].
• Blood pressure: systolic pressure rose by up to 6 mmHg and diastolic by 3 mmHg, peaking 2 to 4 hours after a dose, with heart rate falling by up to 5 beats per minute; values usually returned to baseline within 12 hours [Approved label]. An ambulatory monitoring trial in 397 women found rises of about 3 mmHg at 1.75 mg [Human RCT, n=397] (White 2017).
• Hyperpigmentation: focal darkening of the face, gums or breasts in 1% of trial users, 38% after 8 daily doses and a further 14% after 8 more; it was more likely with darker skin, and resolution was not confirmed in all patients [Approved label].
• Liver: one case of acute hepatitis, with liver enzymes over 40 times the upper limit, occurred in the open-label extension; a role for the drug could not be excluded [Approved label, single case].
• Interactions: it may slow stomach emptying and lower absorption of oral drugs, and may significantly reduce exposure to oral naltrexone, so the label says to avoid that combination [Approved label].

Who should not use it, per the label: people with uncontrolled high blood pressure or known cardiovascular disease (contraindicated); it is not recommended for those at high cardiovascular risk. Women who could become pregnant are advised to use effective contraception, because fetal harm occurred in dogs at 16 times human exposure. The sponsor’s program-wide review reported no deaths and mostly mild-to-moderate events (Clayton 2022).

Unregulated “PT-141”: vials sold online as PT-141 are not the approved autoinjector and have no FDA quality oversight. In August 2026 the FDA told one online seller that its “PT-141” was an unapproved new drug, citing the seller’s own descriptions of effects on sexual arousal as evidence of intended human use (FDA warning letter). Italian forensic chemists identified bremelanotide and melanotan II in 8 unknown samples seized by police with anabolic steroids for the bodybuilding black market (Mestria 2021).

Legal and regulatory status

Jurisdiction	Status (checked October 3, 2026)
US FDA	Approved June 21, 2019 as Vyleesi, NDA 210557, prescription only (Drugs@FDA)
US compounding	Components of FDA-approved drugs meet one 503A bulk criterion (FDA 503A); other 503A conditions still apply
US “research” sales	“PT-141” named as an unapproved new drug, August 24, 2026 (FDA)
WADA 2026	Not named (2026 List)
WADA 2027	Not named; in effect January 1, 2027 (2027 List)
EU	No marketing authorization in EMA’s medicines data (EMA)

The approval is narrow. The label limits use to premenopausal women whose low desire is acquired, generalized and not explained by another medical or psychiatric condition, relationship problems or a medicine, and it states that the drug is not indicated to enhance sexual performance (Vyleesi label). The August 2026 warning letter also covered retatrutide sold as “GLP-3R” (FDA); see our retatrutide entry.

For athletes, WADA’s S0 class bans substances with no current approval by any government health regulator; bremelanotide has US approval and is not named anywhere in the 2026 List (WADA). That does not settle the status of an unlabeled product of unknown content, and anti-doping bodies decide individual cases. Our overview of which peptides WADA prohibits in 2027 covers the classes in detail.

Related peptides

Bremelanotide belongs to the melanocortin class of α-MSH analogues. Its closest relative in the unregulated market is melanotan II, a tanning peptide that forensic chemists describe as not legally marketed and that turned up alongside bremelanotide in the same seized samples (Mestria 2021). Other peptides with pages here include BPC-157, an unapproved peptide often sold by the same “research” sellers.