Skip to content
Terminus Peptides
  • Research use only — not for human or veterinary use
  • 55 compound profiles, every source cited
  • 62 research materials listed
  • Prices published, not hidden behind an enquiry
  • Vials and pre-filled pens
  • Dispatched and supported from the UK
  • Every profile states its UK regulatory status

Research profile · Peptide

PT-141

Also known as Bremelanotide, Vyleesi

Clinical — evidence level 4 of 4: Established clinical evidenceExperimental — UK regulatory status: Experimental — not authorised for human use in the UK

Overview

A melanocortin receptor agonist with genuine phase 3 evidence, approved in the United States but not in the UK.

Category
Peptide
Highest evidence level identified
Established clinical evidence
Last scientifically reviewed
20 August 2026
Last regulatory review
20 August 2026

Mechanism under investigation

Bremelanotide is a synthetic cyclic heptapeptide melanocortin receptor agonist, structurally a derivative of melanotan II, acting principally at the MC3 and MC4 receptors rather than the MC1 pathway that drives pigmentation. Published reviews describe a central rather than vascular mechanism, involving receptor activation and downstream dopamine release in brain regions associated with sexual motivation. That account remains a proposed explanation rather than a settled one.

Research areas

  • Melanocortin signalling
  • Sexual medicine research

These are fields in which the compound has been investigated. Listing a field is not a statement that anything was demonstrated within it.

Current evidence

In-vitro evidence

Cells, tissues or biochemical systems outside a living organism.

Receptor-binding and selectivity work established melanocortin receptor agonism with relative sparing of the pigmentation receptor compared with melanotan II. This is supporting pharmacology rather than efficacy evidence.

Animal evidence

Studies in living non-human animals.

Rodent and primate models of sexual behaviour underpinned development and preceded the human programme.

Human observational evidence

Studies observing people without assigning an intervention.

No meaningful observational literature. Post-marketing experience exists in the United States only and has not been published as cohort evidence.

Clinical-trial evidence

Studies assigning an intervention to human participants.

The strongest evidence base of any compound in its class here. Two identical phase 3 randomised controlled trials in 1,267 premenopausal women reported statistically significant improvement in sexual desire and reduction in associated distress. The important nuance is that effect sizes were modest, and the secondary endpoint of satisfying sexual events showed no significant difference against placebo. Reviewers have explicitly raised placebo response as a concern.

Study limitations

  • Trial populations were restricted to premenopausal women with a specific diagnosis. Findings do not transfer to men, to postmenopausal women, or to other presentations.
  • The co-primary endpoints were patient-reported scales. The more behavioural endpoint did not separate from placebo.
  • Effect sizes were modest and placebo response was high, a recognised problem across this trial literature.
  • Trials were conducted and funded within a commercial development programme, and long-term outcome data beyond the trial periods are limited.

UK regulatory context

Experimental — not authorised for human use in the UK

A compound appearing in research literature that holds no UK authorisation for human use in any indication.

Source: VYLEESI (bremelanotide) prescribing information (opens dailymed.nlm.nih.gov in a new tab) (DailyMed, US National Library of Medicine)

Regulatory classification is jurisdiction-specific. A compound authorised elsewhere is not thereby authorised in the UK, and a supplier’s description of a substance does not determine how it is classified in law. See safety and regulation for the framework and the authoritative sources.

Safety and interpretation

In the phase 3 programme nausea, flushing and headache were each reported in at least one in ten treated participants, with nausea far more common than on placebo; most events were mild or moderate. Transient increases in blood pressure were observed, and the United States label carries a contraindication in uncontrolled hypertension and known cardiovascular disease. Products supplied outside the licensed chain carry the separate risks of unverified identity, purity and sterility.

References