If you have been reading about PT-141 and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-08-06. Where a claim depends on a specific study, the study is described rather than over-claimed.
Bremelanotide is a synthetic cyclic heptapeptide developed under the research code PT-141. The code reflects its position in an internal compound series rather than a chemical classification, and the name bremelanotide was later adopted for regulatory filings. Structurally it belongs to the melanocortin peptide family and shares a core sequence motif with alpha-melanocyte-stimulating hormone. The compound is supplied as an acetate salt in aqueous solution for injection. In reference literature it is indexed under both the code and the generic name, a dual listing that can complicate database searches.
Early work on melanocortin analogs in the 1980s and 1990s produced peptides intended to influence pigmentation and appetite. One of these, melanotan II, was observed to affect sexual desire as an incidental finding in self-administration reports. Researchers then pursued analogs with altered receptor selectivity and improved handling characteristics, and PT-141 emerged from that program in the late 1990s. The development path moved from dermatology and metabolism toward a central nervous system application, a shift that shaped both trial designs and the eventual label.
Regulatory review of bremelanotide concluded in 2019 with approval in the United States for a defined indication in premenopausal women. The reviewed formulation is a single-use prefilled autoinjector given subcutaneously, and its label carries cardiovascular monitoring language tied to blood pressure changes recorded during trials. Availability outside the approving jurisdiction varies, and in several countries the compound remains unapproved or is handled as a prescription-only item. Compounded and research-grade material also circulates, and it differs from the reviewed product in purity, characterization, and chain of custody.
Bremelanotide is a synthetic cyclic heptapeptide developed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation and appetite signalling. Its structure contains seven amino acid residues joined by a lactam bridge that closes the ring between two side chains. The molecular formula is C50H68N14O10 and the nominal molecular mass is near 1025 daltons. Much of the early laboratory literature refers to the same molecule by the development code PT-141.
The compound emerged from a research programme examining melanocortin analogues for effects on skin pigmentation. During early human studies, participants reported spontaneous erections as an unexpected side effect, which redirected development toward sexual function rather than tanning. An intranasal formulation was investigated in clinical trials but did not reach market approval. A subcutaneous injectable version later completed the regulatory process, and the nasal route does not appear in approved labelling.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H68N14O10 | Cyclic heptapeptide core |
| Molecular weight | 1025.2 g/mol | Calculated for the free base |
| CAS registry number | 189691-06-3 | Free base; the acetate salt has a separate entry |
| Solubility class | Water-soluble | Freely soluble in aqueous media near neutral pH |
| Typical storage | 2 to 8 °C | Protect from light; avoid repeated freeze-thaw cycles |
PT-141 is the research code for bremelanotide, a cyclic heptapeptide derived from alpha-melanocyte-stimulating hormone. The molecule belongs to the melanocortin receptor agonist family and shows highest affinity for the MC4 receptor subtype, with weaker activity at MC1, MC3 and MC5. Its structure retains the core His-Phe-Arg-Trp sequence that defines melanocortin recognition, while cyclization and terminal modifications improve metabolic stability relative to the parent hormone. Early work classified the compound as a centrally acting agent rather than a peripherally acting vasodilator, which shaped subsequent development priorities.
Receptor activation in hypothalamic and limbic circuits is the mechanism most often cited for the observed effects on sexual desire. Signalling through MC4R couples to Gs proteins and raises intracellular cyclic AMP, which in turn modulates dopaminergic tone in reward-related pathways. Because the peptide reaches the central nervous system after subcutaneous administration, peripheral vascular changes are regarded as secondary rather than primary. The precise neural circuits that translate receptor occupancy into behavioural change remain incompletely mapped, and published accounts describe the pathway in general terms rather than as a fully resolved sequence.
Bremelanotide is a synthetic cyclic heptapeptide that acts on a family of G-protein-coupled receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide associated with pigmentation and several central signalling pathways. A lactam bridge constrains the ring and slows enzymatic breakdown, which distinguishes it from the linear parent molecule. Research interest moved over time from pigment biology toward central nervous system effects, particularly circuits connected to sexual desire. Parenteral delivery is used because oral bioavailability is poor.
Early clinical work used an intranasal formulation, and later programmes switched to subcutaneous delivery for more consistent absorption. A subcutaneous product received regulatory approval in the United States in 2019 for premenopausal women with acquired, generalised hypoactive sexual desire disorder. Approval followed phase 3 trials in which active treatment separated from placebo on desire and distress measures, though the average difference was modest. Labeling carries a caution about transient blood pressure elevation, so cardiovascular history is assessed before prescribing. Questions about durability of benefit beyond several months remain open.
Lyophilized peptide arrives as a white to off-white cake or powder and is normally held at minus twenty degrees Celsius or colder for extended periods. Short-term bench work at ambient temperature is tolerable for minutes, not hours, because the solid is hygroscopic and picks up moisture that promotes hydrolysis. Vials should stay in a desiccator or a sealed bag with desiccant, protected from light, since aromatic residues in the sequence are susceptible to photo-oxidation. Inventory records that note arrival date and storage location reduce the chance of using degraded material.
Reconstitution is usually performed with sterile water or a dilute acetic acid solution, and the choice of solvent affects both dissolution speed and final pH. Complete dissolution should be confirmed by visual inspection before any aliquot is taken, since undissolved particles can concentrate in the sampling volume. Repeated freeze-thaw cycles are the most common cause of gradual loss of purity, so dividing a stock into single-use aliquots at the first opportunity is standard practice. Working solutions kept refrigerated are generally used within days rather than weeks.
The origin of the modern smallpox vaccine has long been unclear, but horsepox was identified in the 2010s as the most likely ancestor. Edward Jenner had obtained his vaccine from a cow, so he named the virus vaccinia, after the Latin word for cow. Jenner believed that both cowpox and smallpox were viruses that originated in the horse and passed to the cow, and some doctors followed his reasoning by inoculating their patients directly with horsepox. The situation was further muddied when Louis Pasteur developed techniques for creating vaccines in the laboratory in the late 19th century. As medical researchers subjected viruses to serial passage, inadequate recordkeeping resulted in the creation of laboratory strains with unclear origins. By the late 19th century, it was unknown whether the vaccine originated from cowpox, horsepox, or an attenuated strain of smallpox. In 1939, Allan Watt Downie showed that the vaccinia virus was serologically distinct from the "spontaneous" cowpox virus. This work established vaccinia and cowpox as two separate viral species. The term vaccinia now refers only to the smallpox vaccine, while cowpox no longer has a Latin name. The development of whole genome sequencing in the 1990s made it possible to compare orthopoxvirus genomes and identify their relationships with each other. The horsepox virus was sequenced in 2006 and found to be most closely related to vaccinia. In a phylogenetic tree of the orthopoxviruses, horsepox forms a clade with vaccinia strains, and cowpox strains form a different clade.
== Function == FLAP is necessary for the activation of 5-lipoxygenase and therefore for the production of leukotrienes, 5-hydroxyeicosatetraenoic acid, 5-oxo-eicosatetraenoic acid, and specialized pro-resolving mediators of the lipoxin and resolvin classes. It is an integral protein within the nuclear membrane. FLAP is necessary in synthesis of leukotriene, which are lipid mediators of inflammation that is involved in respiratory and cardiovascular diseases. FLAP functions as a membrane anchor for 5-lipooxygenase and as an amine acid-bind protein. How FLAP activates 5-lipooxygenase is not completely understood, but there is a physical interaction between the two. FLAP structure consists of 4 transmembrane alpha helices, but they are found in trimer forming a barrel. The barrel is about 60 Å high and 36 Å wide.
== Organisational factors == The apartheid government immediately rejected the argument that the uprising was the spontaneous result of residents' political and socioeconomic grievances and instead claimed consistently that it had been orchestrated by organisations with ulterior – and insurrectionary – political motives. This was apparent as early as 6 September 1984, when Minister of Law and Order Louis le Grange, making a tour of the Vaal townships in an armoured vehicle, denied that the violence was about rent increases and said, "There are individuals and other forces and organisations very clearly behind what is happening in the Vaal Triangle".
Sources: en.wikipedia.org
The OECD member countries, each represented by a delegation led by an ambassador. Together, they form the OECD Council. Member countries act collectively through the council (and its standing committees) to provide direction and guidance to the work of the organisation. The OECD substantive committees, one for each work area of the OECD, plus their various subsidiary bodies. Committee members are typically subject-matter experts from member and non-member governments. The committees oversee all the work on each theme (publications, task forces, conferences, and so on). Committee members then relay the conclusions to their capitals. The OECD Secretariat, led by the Secretary-General (currently Mathias Cormann), provides support to standing and substantive committees. It is organised into directorates, which include about 2,500 staff.
=== Professional services === He has fulfilled roles in numerous professional organizations, including the Swedish Biochemical Society (secretary 1976–1982); Chairman of the Swedish National Committee on Biochemistry, Royal Swedish Academy of Sciences, 1988–1990; Chairman Scientific Program Committee for the 22nd Meeting of the Federation of European Biochemical Societies, FEBS 1993; editorial boards of the Biochemical Journal, ChemBioChem, Biochimica et Biophysica Acta, Protein Engineering Design and Selection, the Journal of Biological Chemistry. In addition, he has had advisory roles at various companies: Telik Inc.; PanVera Corporation, Pharmacia Biotech; Uniroyal Chemical Company; Biovitrum AB; Maxygen; Vividion; Oxford Biomedical Research, Rochester Hills, Michigan.
=== Biosignaling === For isopeptide bonds linking one protein to another for the purpose of signal transduction, the literature is dominated by ubiquitin and other similar proteins. Ubiquitin and its related proteins (SUMO, Atg8, Atg12, etc.) all tend to follow relatively the same protein ligation pathway. The process of protein ligation by ubiquitin and ubiquitin-like proteins has three main steps. In the initial step, the specific activating protein (E1 or E1-like protein) activates Ubiquitin by adenylating it with ATP. Then the adenylated Ubiquitin can be transferred to a conserved cysteine using a thioester bond which is between the carboxyl group of the C-terminal glycine of the ubiquitin and the sulfur of the E1 cysteine. The activating E1 enzyme then binds with and transfers the Ubiquitin to the next tier, the E2 enzyme which accepts the protein and once again forms a thioester with a conserved bond. The E2 acts to certain degree as an intermediary which then binds to E3 enzyme ligase for the final tier, which leads to the eventual transfer of the ubiquitin or ubiquitin related protein to a lysine site on the targeted protein, or more commonly for ubiquitin, onto ubiquitin itself to form chains of said protein. However, in final tier, there is also a divergence, in that depending on the type of E3 ligase, it may not actually be causing the conjugation.
Sources: en.wikipedia.org
PT-141 was the internal development code assigned to bremelanotide during preclinical research. Reference sources sometimes index the peptide under the code rather than the generic name. The two terms describe the same molecule.
They are related but distinct cyclic peptides. Melanotan II is an earlier and less selective melanocortin analog. Bremelanotide was developed later with a narrower receptor profile and a defined clinical application.
The reviewed product is given by subcutaneous injection using a single-use autoinjector. Administration occurs under prescription supervision. The device delivers one fixed amount per use rather than a measured or adjustable quantity.
It is a synthetic cyclic peptide that acts as an agonist at melanocortin receptors. It is not a hormone replacement therapy and not a vasodilator in the usual clinical sense, although it does affect vascular tone. Chemically it belongs to the melanocortin analogue family.