PT-141

What it is

Bremelanotide is closely related to melanotan 2, the tanning peptide of the scene. Both mimic the body’s own alpha-MSH, a hormone that acts on a whole family of receptors, the melanocortin receptors, and both are cyclic heptapeptides, that is, peptides of 7 building blocks closed into a ring. Already in the first human study of melanotan 2 in 1996, the participants experienced spontaneous erections. This finding prompted research into melanocortins for sexual medicine, and the company Palatin Technologies developed bremelanotide through to approval.

Early studies were conducted in men, with injections and with a nasal spray. In the end, however, an injection for women was approved: in 2019 the US drug regulator approved Vyleesi for premenopausal women with acquired, generalized hypoactive sexual desire disorder, HSDD in technical jargon. The prescribing information explicitly states that it is not intended for men, for women after menopause or to enhance sexual performance.

How it works

Bremelanotide binds with high affinity to the MC4 receptor, which sits in brain regions involved in sexual motivation. The idea is that desire is not just a matter of blood flow but arises in the brain and can be influenced there. This fundamentally distinguishes PT-141 from PDE5 inhibitors such as sildenafil or tadalafil, which act on the blood vessels.

Because it docks onto several melanocortin receptors, it also brings their other effects: nausea, flushing of the face, a brief rise in blood pressure and, with repeated doses, darker skin patches, a legacy of its kinship with the tanning peptide.

In a 2007 review, the developer emphasized that melanocortins, unlike PDE5 inhibitors, do not cause a drop in blood pressure, and pointed to animal experiments in which female rats given such agents showed behaviors corresponding to sexual arousal. The later approval painted a more precise picture: instead of a drop, blood pressure rises briefly after each dose, which is why the US regulator explicitly excludes people with cardiovascular disease.

What has been studied in men

In the scene, PT-141 is used mainly by men, as an alternative or supplement to erectile dysfunction drugs. There are in fact controlled data on this, though no approval. In 2004, injections in healthy men and in men whom Viagra did not help sufficiently triggered measurable erections compared with placebo. In 2005, a PT-141 nasal spray in a crossover study with 19 men enhanced the effect of a low sildenafil dose without any new side effects occurring.

The largest study in men, from 2008, with 342 men in whom sildenafil had failed, reported a positive result in 33.5 percent on PT-141 versus 8.5 percent on placebo. In 2023, however, the journal published an expression of concern about this paper, an official reservation, after doubts had arisen about numerous papers by the same author. Its numbers should therefore be read only with caution.

What the studies show

Kingsberg et al. 2019 — RECONNECT, the pivotal trials

Two phase 3 trials, randomized, double-blind, placebo-controlled, 1,267 premenopausal women with HSDD, 24 weeks, use as needed. Both co-primary endpoints met; the effect is moderate. Nausea, flushing and headache were more frequent than on placebo.

Simon et al. 2019 — 52-week extension

Open-label continuation; 684 of 856 eligible women took part, 272 completed it. The most common treatment-related side effects were nausea in 40.4 percent, flushing in 20.6 percent and headache in 12.0 percent.

Diamond et al. 2005 — combination with sildenafil in men

Randomized crossover study with 19 men with erectile dysfunction. Nasal spray plus low-dose sildenafil led to stronger erections than sildenafil alone, without new or more frequent side effects. Small and short, but controlled.

Where the data stop

PT-141 is approved and tested on a large scale only for premenopausal women with a diagnosed desire disorder. For men there are smaller studies and a larger one that is now under a reservation, but no approval program. For women after menopause, for people without a desire disorder and for performance enhancement, robust data are lacking, and the US prescribing information explicitly excludes these uses.

Even in women, the effect is not a switch that gets flipped. The differences from placebo are statistically clear but modest in absolute points, and some of the women discontinue because of nausea. Gray-market products, nasal sprays from the scene and self-mixed solutions are, moreover, not the tested preparation; an independent analysis of gray-market samples of 14 peptides, including PT-141, found quality defects in 41.6 to 71.1 percent.

Status, approval and legal

Bremelanotide has been approved in the US as Vyleesi since 2019, exclusively for premenopausal women with acquired, generalized HSDD. It was developed by Palatin Technologies; the rights for North America went to AMAG Pharmaceuticals, which submitted the application for approval to the FDA. Since the end of 2023, Cosette Pharmaceuticals has marketed the drug in the US. No approval is documented in the EU or in Germany; here it is available only via the gray market. It is not listed by name on the WADA prohibited list. We do not give dosage information for the use that is not approved in Germany.

Safety

The US prescribing information is clear. Bremelanotide must not be used in uncontrolled high blood pressure or known cardiovascular disease. After each dose, blood pressure rises temporarily by up to 6 mmHg systolic and 3 mmHg diastolic, peaking after 2 to 4 hours; the pulse falls by up to 5 beats, and after usually 12 hours everything is back within the baseline range. Nausea occurred in 40 percent; 13 percent needed medication for it, 8 percent discontinued. In 1 percent, dark patches appeared on the face, gums or breasts, more often with darker skin and daily use, and they did not always resolve. Bremelanotide can slow gastric emptying and markedly reduces the absorption of orally taken naltrexone. If pregnancy is suspected, it should be discontinued.

Sources

• Kingsberg et al., Obstetrics and Gynecology 2019
• Simon et al., Obstetrics and Gynecology 2019
• FDA, prescribing information Vyleesi 2019
• Shadiack et al., Current Topics in Medicinal Chemistry 2007 – melanocortins in sexual medicine
• Toledo et al., Journal of Minimally Invasive Gynecology 2026
• Rosen et al., International Journal of Impotence Research 2004
• Diamond et al., Urology 2005
• Safarinejad & Hosseini, Journal of Urology 2008
• Journal of Urology 2023 – expression of concern about Safarinejad 2008
• Mendias & Awan, preprint 2026 – quality of gray-market peptides