PT-141 (bremelanotide): how it works, studies and approval

Bremelanotide may offer a limited benefit to premenopausal women with a specific disorder of sexual desire. That is what studies of the approved medicine Vyleesi show. This finding does not carry over to products sold on the gray market under the name “PT-141”: their efficacy and safety in the form in which they are sold have not been established.

What is PT-141?

PT-141 is the name under which bremelanotide is known in research and on the gray market. The drug belongs to the cyclic melanocortin peptides. The US Food and Drug Administration (FDA) has approved it under the brand name Vyleesi for premenopausal women with acquired, generalized low sexual desire. The medical term is hypoactive sexual desire disorder, or HSDD. “Acquired” means the disorder developed at some point in life; “generalized” means it is not limited to particular situations.

Suppliers of research chemicals and of individually compounded preparations also sell products under the name “PT-141.” They are often marketed for boosting libido in men and women. These products are not equivalent to the approved medicine Vyleesi.

How does it work?

PT-141 (bremelanotide) activates melanocortin receptors, mainly MC4R, in brain regions that help regulate sexual desire. In other words, the drug acts in the brain. Medicines for erectile dysfunction, by contrast, work on blood flow.

Exactly how activating these receptors affects sexual desire is not yet understood. And the proposed mechanism on its own does not show that an unregulated product, in the form in which it is sold, is effective or safe.

Is it FDA-approved?

The FDA approval applies to Vyleesi. It does not extend to “PT-141” sold on the gray market. The groups of people the products are marketed to also differ:

Feature	Vyleesi (bremelanotide)	Gray-market “PT-141”
FDA status	FDA-approved since 2019	Not approved as Vyleesi; unregulated source. The blanket claim that such products are not subject to any FDA quality control has not been verified.
Population	Premenopausal women with HSDD	Marketed to men and for boosting libido in general

Vyleesi is self-injected as needed.

What does the research show?

The solid clinical data come from studies of the approved medicine in premenopausal women with HSDD. The review of the initial approval [1] describes the phase 3 trials on which the approval is based. An independent analysis [2] judged the measured benefit to be small and criticized the outcome measures used.

There are no controlled studies supporting broader use of gray-market products sold as “PT-141” to boost libido in either sex. The benefits and safety of these products in the form in which they are sold have therefore not been established.

Frequently asked questions

What is PT-141, and how is it different from Viagra or Cialis?

PT-141 (bremelanotide) influences sexual desire through the central nervous system. Viagra and Cialis act on the smooth muscle of blood vessels outside the central nervous system and improve blood flow. That means they intervene at a different point in the sexual response.

Bremelanotide activates melanocortin receptors [3], especially MC4R. These receptors are found in many areas of the central nervous system. Exactly how activating them improves sexual desire is not known.

Viagra and Cialis are PDE5 inhibitors. They prevent the breakdown of the messenger molecule cyclic GMP [4], or cGMP, in the smooth muscle of the penis. This supports sustained blood inflow and with it the physical processes of an erection. Sexual stimulation is still required.

What did the RECONNECT trials show for bremelanotide in HSDD?

In the RECONNECT phase 3 program, premenopausal women with HSDD showed statistically significant improvements in sexual desire and related distress compared with placebo. The differences, however, were small.

The program comprised two randomized controlled trials with a total of 1,267 participants. They received either bremelanotide at a dose of 1.75 mg or placebo as a subcutaneous injection, meaning under the skin. The injections were used as needed over 24 weeks.

In the desire domain of the Female Sexual Function Index (FSFI) [5], the score rose 0.35 points more with bremelanotide than with placebo (P < 0.001; Study 301: +0.30; Study 302: +0.42). On item 13 of the Female Sexual Distress Scale–Desire/Arousal/Orgasm (FSDS-DAO), the score fell 0.33 points more than with placebo (P < 0.001). This question captures distress related to sexual desire. So the numbers describe changes in questionnaire scores: on the FSFI, a higher score means more desire; on this FSDS-DAO question, a lower score means less distress.

A 52-week open-label extension study enrolled 684 women. The researchers observed sustained improvements [6]. In women who had already received bremelanotide in the main trials, the FSFI desire score was 1.25–1.30 points above baseline, and the FSDS-DAO score was 1.4–1.7 points below it. No new safety signals were found. Unlike in the main trials, these numbers refer to changes from baseline in an open-label study. They are therefore not equivalent to the differences between bremelanotide and placebo.

An independent analysis from 2024 [2] rated the statistically measured benefit as small and questioned how meaningful the outcome measures are.

Who is PT-141 FDA-approved for?

The FDA has approved bremelanotide, under the name Vyleesi, for premenopausal women with acquired, generalized HSDD. The approval therefore covers a specific disorder of sexual desire, not general use to boost libido.

Vyleesi was approved in June 2019 [7]. After flibanserin (Addyi) in 2015, it was the second drug treatment for HSDD approved by the FDA [8] and the first to be used as needed.

In men, bremelanotide is not FDA-approved for any indication [3].

How does bremelanotide affect sexual desire in the brain?

Bremelanotide activates melanocortin-4 receptors (MC4R), which are found in many areas of the central nervous system. It appears to heighten the brain’s response to erotic cues. Amplifying signals outside the central nervous system is not the focus of this explanation.

A 2022 crossover study using functional magnetic resonance imaging (fMRI) [9] examined 31 premenopausal women with HSDD. In this study design, the same participants received both bremelanotide and placebo at different times. The bremelanotide dose was 1.75 mg, injected under the skin. Using fMRI, the researchers examined how the brain responded to erotic visual stimuli.

With bremelanotide, activity in the cerebellum and the supplementary motor area in response to these stimuli was significantly stronger (Z = 2.3; P < 0.05). At the same time, activity in the secondary somatosensory cortex decreased. Activity in the amygdala and insula was more strongly coupled (F(1,30) = 5.55; P = 0.025).

One possible interpretation of these findings is that bremelanotide reduces self-consciousness, heightens sexual imagery and increases receptiveness to erotic cues. The measured changes in brain activity, however, do not conclusively prove this explanation.

Is there evidence for PT-141 in men?

Early randomized controlled trials suggest that bremelanotide (PT-141) may promote erections in men. There are no phase 3 trials in men, and it is not FDA-approved for men for any indication.

A 2004 study tested PT-141 given intranasally, meaning through the nose. Participants were healthy men and men with erectile dysfunction (ED) who responded to Viagra. At doses above 7 mg, there was a statistically significant erectile response [10], measured with RigiScan. The first erection began after about 30 minutes.

In a second 2004 study, healthy men received PT-141 as an injection under the skin at doses of 0.3–10 mg. Significant erectile responses occurred at doses above 1.0 mg. A crossover component also included men with ED who had responded inadequately to Viagra. In this group, doses of 4 mg and 6 mg [11] produced statistically significant erectile responses compared with placebo.

These results come from early stages of development. They do not establish an approved use in men and are no substitute for a randomized controlled phase 3 trial.

What side effects have been documented with bremelanotide?

The side effects of bremelanotide documented most often in studies include nausea, episodes of skin reddening with a feeling of warmth (flushing) and headache.

A 2016 randomized controlled dose-finding study [12] enrolled 327 premenopausal women for 12 weeks. At doses of 0.75–1.75 mg injected under the skin, nausea, flushing and headache occurred. In the 52-week open-label extension of the phase 3 trials [6], the researchers found no new safety signals. That does not mean the side effects already known were absent.

A 2025 narrative review [8] recommended using HSDD medicines, including bremelanotide, with restraint. It cited their limited efficacy and possible side effects as the reasons.

Sources

• Sources: a review of bremelanotide’s approval (Dhillon and Keam, Drugs, 2019, DOI: 10.1007/s40265-019-01187-w 1 ) and an independent critique of the trial outcomes (Spielmans and Ellefson, Journal of Sex Research, 2024, DOI: 10.1080/00224499.2023.2175192 2 ), indexed on PubMed; and FDA records for the approved product Vyleesi. This document is educational, is not medical advice or a health claim, and is not an offer to sell any product. Original reference Original reference