PT-141 (Bremelanotide): Structure, Research Overview and Specifications
PT-141, also known as bremelanotide, is a synthetic cyclic peptide that activates melanocortin receptors in the central nervous system, mainly the MC4 receptor. It was developed from melanotan II and is studied in research on melanocortin signalling in the brain. This page summarises its chemistry, the published research and the specifications of the material we supply.
For in vitro research use only. Not for human or animal use. Nothing on this page is medical advice.
What is PT-141?
PT-141 is a seven-amino-acid peptide closed into a ring structure, which makes it more stable than a linear peptide of the same length. It belongs to the melanocortin family of compounds, which are modelled on alpha-melanocyte-stimulating hormone (alpha-MSH).
Unlike compounds that act on blood vessels or peripheral tissues, PT-141 acts mainly on receptors in the brain. This makes it a research tool for studying how the central melanocortin system influences behaviour and motivation.
Chemical data
| Name | PT-141 (Bremelanotide) |
|---|---|
| Other names | Bremelanotide, Vyleesi (US brand name) |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH |
| Structure | Cyclic heptapeptide (lactam bridge between Asp and Lys) |
| Molecular formula | C50H68N14O10 |
| Molecular weight | ≈ 1025.2 g/mol |
| CAS number | 189691-06-3 |
| Form supplied | Lyophilised (freeze-dried) powder |
Origin: from melanotan II
PT-141 was developed from melanotan II, a synthetic analogue of alpha-MSH originally studied at the University of Arizona for skin pigmentation. During that research, investigators observed effects that appeared to come from the brain rather than the skin.
Researchers then created PT-141 as a closely related compound with a free acid end instead of an amide. It was developed further by Palatin Technologies and studied as a centrally acting melanocortin receptor agonist.
Proposed mechanisms studied
- MC4 receptorPT-141 acts mainly as an agonist at the melanocortin-4 receptor (MC4R), which is found in areas of the brain such as the hypothalamus.
- MC3 receptorIt also activates the MC3 receptor, which is involved in energy balance and other central functions.
- Dopamine pathwaysResearch suggests that MC4R activation in the hypothalamus may influence dopamine release in brain areas involved in motivation.
- Central, not vascularIts effects in animal models are attributed to brain signalling rather than to direct action on blood vessels.
What the published research shows
Animal behaviour studies
Studies in female rats reported that a melanocortin receptor agonist selectively increased solicitation behaviour, supporting a central role for melanocortin signalling in motivated behaviour.
Early clinical development
Early clinical studies first examined intranasal delivery, which was later replaced because of effects on blood pressure. Development then moved to a subcutaneous formulation.
Phase 3 clinical trials
Two phase 3 trials (RECONNECT) studied bremelanotide in premenopausal women with hypoactive sexual desire disorder, measuring changes in desire and related distress against placebo. These trials supported its US approval.
Reported adverse events in trials
In clinical trials, the most commonly reported adverse events included nausea, flushing and headache. Transient increases in blood pressure and focal skin darkening were also reported.
Limitations of the evidence
- Clinical evidence comes from specific, defined patient populations and cannot be generalised to other groups.
- The effect sizes reported in phase 3 trials were modest compared with placebo.
- The exact pathway from MC4R activation to behavioural effects is still being studied.
- Research-grade material is not the same as the licensed medicinal product.
Regulatory status
Bremelanotide was approved by the US FDA in 2019 under the brand name Vyleesi for a specific indication. It is not approved in the UK. The PT-141 we supply is a research-grade compound, not a licensed medicinal product, and is sold strictly for in vitro laboratory research. It is not intended for human or animal use.
Storage and handling in the lab
- Store lyophilised powder at −20 °C, protected from light and moisture, for long-term stability.
- Allow the vial to reach room temperature before opening to reduce condensation.
- Once reconstituted for experiments, keep refrigerated (2–8 °C) and avoid repeated freeze–thaw cycles.
- PT-141 contains a tryptophan residue, which can be sensitive to light; protect solutions from light exposure.
Quality
Every batch of PT-141 we supply is independently tested for purity by Janoshik using HPLC before it is released for sale. Read more on our Quality & Testing page.
Related research compounds
Frequently asked questions
Is PT-141 the same as bremelanotide?
Yes. PT-141 is the research code for bremelanotide, a cyclic melanocortin receptor agonist.
What is the difference between PT-141 and melanotan II?
PT-141 was developed from melanotan II. The two are structurally very similar, but PT-141 has a free acid end instead of an amide and was developed for research on central melanocortin signalling rather than skin pigmentation.
Which receptors does PT-141 act on?
PT-141 acts mainly on the melanocortin-4 receptor (MC4R) in the brain, and also on the melanocortin-3 receptor (MC3R).
Is PT-141 approved in the UK?
No. Bremelanotide was approved in the US in 2019 for a specific indication, but it is not approved in the UK. Our product is a research-grade compound supplied strictly for laboratory research.
How should PT-141 be stored?
Lyophilised PT-141 should be stored at −20 °C, protected from light and moisture. Reconstituted solutions should be kept refrigerated, protected from light and not repeatedly frozen and thawed.
References
- Molinoff PB, et al. PT-141: a melanocortin agonist for the treatment of sexual dysfunction. Annals of the New York Academy of Sciences. 2003;994:96–102.
- Pfaus JG, et al. Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonist. Proceedings of the National Academy of Sciences USA. 2004;101(27):10201–10204.
- Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstetrics & Gynecology. 2019;134(5):899–908.
- Dhillon S, Keam SJ. Bremelanotide: first approval. Drugs. 2019;79(14):1599–1606.
This page is for scientific information only. Sterling Research Group Ltd supplies PT-141 strictly for in vitro laboratory research. Not for human or animal use, and not for diagnostic or therapeutic purposes. Questions: [email protected]