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PT-141 (bremelanotide) is a synthetic cyclic peptide that activates melanocortin receptors in the brain, mainly MC4R. It was developed from Melanotan 2 and became the first melanocortin agonist approved for a sexual-function indication when the US FDA approved it as Vyleesi in 2019. This overview covers where PT-141 came from, how it works, what clinical trials reported and its UK status.
What is PT-141?
PT-141 is a cyclic heptapeptide and a close derivative of Melanotan 2. It differs by a single change at the C-terminus (a carboxylic acid instead of an amide), which shifts its receptor profile towards the brain’s MC4 and MC3 receptors.
Key facts
- Names: PT-141, bremelanotide, Vyleesi (US brand)
- Structure: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH
- Approx. molecular weight: 1,025 Da
- Developer: Palatin Technologies
Where PT-141 came from
Early Melanotan 2 studies at the University of Arizona recorded unexpected effects on sexual arousal alongside tanning. Palatin licensed the work and developed PT-141 to keep the central effects while reducing the pigmentation activity.
Development timeline
- Early 2000s: intranasal PT-141 trialled in men and women.
- 2008: intranasal programme halted after blood pressure increases were seen in trials.
- 2010s: reformulated as a subcutaneous injection and tested in the RECONNECT phase 3 trials.
- June 2019: FDA approval as Vyleesi for acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women.
How PT-141 works
Unlike PDE5 inhibitors, which act on blood flow, PT-141 acts centrally on brain pathways.
- MC4R activation: MC4 receptors in the hypothalamus are linked to sexual motivation and energy balance.
- Dopamine involvement: research suggests MC4R activation increases dopamine release in regions linked to desire.
- Less MC1R activity: weaker action on pigment cells than Melanotan 2, though not zero.
What the clinical trials reported
In the RECONNECT phase 3 trials, bremelanotide showed statistically significant improvements in desire scores and reduced related distress compared with placebo.
Reported adverse effects
- Nausea: the most common, reported by a large share of trial participants.
- Flushing and headache.
- Transient blood pressure increase after each administration.
- Focal hyperpigmentation (darkening of areas such as the face and gums) in a small number of participants.
These findings come from a licensed, pharmaceutical-grade product under medical supervision and do not apply to research material.
PT-141 vs Melanotan 2
| PT-141 | Melanotan 2 | |
|---|---|---|
| Main receptors | MC4R, MC3R | MC1R, MC3R, MC4R, MC5R |
| Pigmentation activity | Low | High |
| Licensed anywhere? | US only (Vyleesi) | No |
UK status
- Not licensed in the UK or EU: bremelanotide has no MHRA or EMA marketing authorisation.
- Research use only: PeptidesNextDay supplies PT-141 for laboratory research and not for human use. See are peptides legal in the UK?
For handling, see our reconstituting and storage guide and peptide calculator.
PT-141 FAQs
Is PT-141 the same as bremelanotide?
Yes. PT-141 was the development code used by Palatin Technologies; bremelanotide is the generic name. Vyleesi is the US brand name of the approved medicine.
How is PT-141 different from Melanotan 2?
PT-141 is derived from Melanotan 2 but is more focused on the MC4 and MC3 receptors in the brain, with less pigmentation activity.
Is PT-141 approved in the UK?
No. Bremelanotide is approved only in the US (as Vyleesi). It has no UK or EU marketing authorisation and is supplied in the UK for research use only.
Is PT-141 a hormone?
No. It is a synthetic peptide that activates melanocortin receptors in the brain rather than acting on sex hormone levels.
Summary
PT-141 is a Melanotan 2 derivative that acts on brain MC4 receptors. It is approved in the US as Vyleesi but unlicensed in the UK. For laboratory research, PeptidesNextDay stocks PT-141 (Bremelanotide) 10mg at ≥98% purity, with batch documentation available on request.