This is a working overview of bremelanotide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-11-05 and is reviewed periodically as new material appears.
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.
Bremelanotide, developed under the code PT-141, is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone. Its structure is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, with a lactam bridge joining the aspartate and lysine side chains. The molecule has the formula C50H68N14O10 and a monoisotopic mass near 1025 daltons. It is commonly prepared as the acetate salt and appears as a white to off-white lyophilised powder in solid form. The free acid is the pharmacologically relevant species, while the counter-ion improves handling and dissolution.
Early research on PT-141 grew out of work on melanotan II, a related cyclic peptide studied for pigmentation. Investigators observed that centrally acting melanocortin agonists also influenced sexual behaviour in animal models, and the programme shifted toward that endpoint. A nasal formulation was evaluated in clinical trials but showed inconsistent absorption, and later studies used subcutaneous administration instead. Regulatory approval in the United States followed in 2019 for a defined population of premenopausal women with acquired, generalised hypoactive sexual desire disorder. That approval was specific to that group rather than a broad indication.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-MSH |
| Molecular mass | Approximately 1025 Da | Peptide-scale molecule |
| Route | Subcutaneous injection | Intranasal form used in early research |
| Common synonyms | PT-141; bremelanotide acetate | Research code and salt form |
| Typical storage | 2-8 °C, protected from light | Unopened vial condition |
The melanocortin system comprises five G protein-coupled receptors, designated MC1 through MC5, that signal mainly through cyclic AMP accumulation. MC1R and MC2R are associated with pigmentation and adrenal steroid production, while MC3R and MC4R are expressed in the central nervous system and influence energy balance and behavior. MC5R appears in exocrine tissues. Natural agonists include alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone, and endogenous antagonists such as agouti-related protein modulate the same sites. This receptor family provides the framework within which bremelanotide activity is described.
Bremelanotide acts as an agonist at several melanocortin receptors, with the strongest reported activity at MC4R and measurable activity at MC1R and MC3R. Because MC4R is expressed in hypothalamic and limbic circuits, the proposed mechanism links receptor activation to modulation of central pathways involved in desire rather than to direct effects on peripheral genital tissue. The precise downstream steps remain incompletely characterized, and evidence for the involvement of specific neurotransmitters is suggestive rather than settled. Nausea and blood pressure elevation reported during trials are consistent with melanocortin signaling outside the intended target circuit.
In 2004, development of an antisense therapy for spinal muscular atrophy began. Over the following years, an antisense oligonucleotide later named nusinersen was developed by Ionis Pharmaceuticals under a licensing agreement with Biogen. In December 2016, nusinersen received regulatory approval from FDA and soon after, from other regulatory agencies worldwide. As of 2020, more than 50 antisense oligonucleotides were in clinical trials, including over 25 in advanced clinical trials (phase II or III). A follow-on drug to Inotersen is being developed by Ionis Pharmaceuticals and under license to Akcea Therapeutics for hereditary transthyretin-mediated amyloidosis. In this formulation the ASO is conjugated to N-Acetylgalactosamine enabling hepatocyte-specific delivery, greatly reducing dose requirements and side effect profile while increasing the level of transthyretin reduction in patients.
3-Aminoacetanilide is a chemical compound which is an amino derivative of acetanilide and meta-isomer of aminoacetanilide. There are two other isomers of aminoacetanilide, 2-aminoacetanilide and 4-aminoacetanilide. Aminoacetanilide derivatives are important synthetic intermediates in heterocyclic and aromatic synthesis. These derivatives have found applications in pharmaceutical industry and dyes and pigment industry. A number of methods are available to synthesize 3'-aminoacetanilide. It could be prepared by reduction of m-nitroacetanilide. m-Chloroacetanilde has been converted into m-aminoacetanilide. 3′-Aminoacetanilide has been used in the preparation of azo compounds, pyrrole, imidazole, thiazole and other heterocycles. It is starting material for Trametinib. It is also used to prepare reactive yellow K-RN and dispersed dye.
C4H2N2O4 + GSH → C4H3N2O4• + GS• C4H3N2O4• + GSH → C4H4N2O4 + GS• C4H4N2O4 + O2 → C4H3N2O4• + O2•− + H+ C4H3N2O4• + O2 → C4H2N2O4 + O2•− + H+ Because it selectively kills the insulin-producing beta-cells found in the pancreas, alloxan is used to induce diabetes in laboratory animals. This occurs most likely because of selective uptake of the compound due to its structural similarity to glucose as well as the beta-cell's highly efficient uptake mechanism (GLUT2). In addition, alloxan has a high affinity to SH-containing cellular compounds and, as a result, reduces glutathione content. Furthermore, alloxan inhibits glucokinase, a SH-containing protein essential for insulin secretion induced by glucose. Most studies have shown that alloxan is not toxic to the human beta-cell, even in very high doses, probably because of differing glucose uptake mechanisms in humans and rodents. Alloxan is, however, toxic to the liver and the kidneys in high doses, as these are tissues where the GLUT2 transporter is expressed in humans. Streptozotocin
Sources: en.wikipedia.org
The Hmd holoenzyme includes the protein homodimer as well as its associated iron-containing cofactor. Several species of methanogens have been characterized that express enzymes in the Hmd hydrogenase family. Between species the enzyme is found with differing numbers of sub-units and some minor amino acid sequence variations. The monomer is approximately 45,000 Da in mass, although this value varies from species to species. The enzymatic activity of the enzyme is lost upon exposure to sunlight or UV. Photolysis causes the release of an iron atom and two molecules of carbon monoxide. In the holoenzyme the Fe and CO molecules are found associated with a 542 Da cofactor.
In molecular biology, ATP10 protein (mitochondrial ATPase complex subunit ATP10) is an ATP synthase assembly factor. It is essential for the assembly of the mitochondrial F1-F0 complex. A yeast nuclear gene (ATP10) encodes a product that is essential for the assembly of a functional mitochondrial ATPase complex. Mutations in ATP10 induce a loss of rutamycin sensitivity in the mitochondrial ATPase, but do not affect the respiratory enzymes. ATP10 has a molecular weight of 30,293 Da and its primary structure is not related to any known subunit of the yeast or mammalian mitochondrial ATPase complexes. ATP10 is associated with the mitochondrial membrane. It is suggested that the ATP10 product is not a subunit of the ATPase complex but rather a protein required for the assembly of the F0 sector of the complex.
Anti-citrullinated protein antibodies (ACPAs) are autoantibodies (antibodies to an individual's own proteins) that are directed against peptides and proteins that are citrullinated. They are present in the majority of patients with rheumatoid arthritis. Clinically, cyclic citrullinated peptides (CCP) are frequently used to detect these antibodies in patient serum or plasma (then referred to as anti–citrullinated peptide antibodies). During inflammation, arginine amino acid residues can be enzymatically converted into citrulline residues in proteins such as vimentin, by a process called citrullination. If their shapes are significantly altered, the proteins may be seen as antigens by the immune system, thereby generating an immune response. ACPAs have proved to be powerful biomarkers that allow the diagnosis of rheumatoid arthritis (RA) to be made at a very early stage. In July 2010, the 2010 ACR/EULAR Rheumatoid Arthritis Classification Criteria were introduced. These new classification criteria include ACPA testing, and overruled the "old" ACR criteria of 1987 and are adapted for early RA diagnosis.
Sources: en.wikipedia.org
miR-324-5p is a microRNA that functions in cell growth, apoptosis, cancer, epilepsy, neuronal differentiation, psychiatric conditions, cardiac disease pathology, and more. As a microRNA, it regulates gene expression through targeting mRNAs. Additionally, miR-324-5p is both an intracellular miRNA, meaning it is commonly found within the microenvironment of the cell, and one of several circulating miRNAs found throughout the body. Its presence throughout the body both within and external to cells may contribute to miR-324-5p's wide array of functions and role in numerous disease pathologies – especially cancer – in various organ systems.
39. Izv Akad Nauk Ser Biol. 2001 Sep-Oct;(5):517-21. [Rhythm of protein synthesis in cultures of hepatocytes from rats of different ages. Norm and effect of the peptide livagen]. [Article in Russian] Brodskiĭ VIa, Khavinson VKh, Zolotarev IuA, Nechaeva NV, Malinin VV, Novikova TE, Gvazava IG, Fateeva VI. The circumhoralian rhythm of protein synthesis was determined in a monolayer culture of hepatocytes from rats at the age of 1 to 24 months and weighing from 45 to 480 g, respectively. The peptide lyvagen (Lys-Glu-Asp-Ala) obtained by directed chemical synthesis on the basis of amino acid analysis of the liver polypeptide preparations increased the level of protein synthesis in the hepatocytes from rats of different ages; the highest effect was observed in the cells of old animals. In old rats, lyvagen increased the amplitude of protein synthesis fluctuations. The peptide epitalon (Ala-Glu-Asp-Gly) constructed on the basis of analysis of the epiphysis peptides did not change the intensity of protein synthesis in the cultured hepatocytes.
Gas exchange must be restored as quickly as possible to avoid collateral damage, so activated lymphocytes secrete IFNγ to stimulate the production of matrix metalloproteinase MMP-9 by macrophages. AMs have been reported to produce MMP-9 partly via PGE2-dependent PKA signaling pathways, which are the pathways involved in the inhibition of phagocytosis. MMP-9 activates latent TGF-β, reinducing expression of αvβ6 integrins on alveolar epithelial cells, thereby returning the alveolar macrophage to a resting state. Activation of TGF-β is also advantageous because its production stimulates collagen synthesis in interstitial fibroblasts, which is necessary for restoring alveolar wall architecture. List of human cell types derived from the germ layers Histology image: 13906loa – Histology Learning System at Boston University - "Respiratory System: lung (human), alveolar macrophages" Histology at KUMC resp-resp16 "Alveoli" Slide at ufl.edu
ANGPTL8 (also known as lipasin, previously betatrophin) is a protein that in humans is encoded by the C19orf80 gene. The ANGPTL8 gene lies on mouse chromosome 9 (gene symbol: Gm6484) and on human chromosome 19 (gene symbol: C19orf80). The ANGPTL8 gene was discovered in 2012 as Lipasin, RIFL, and ANGPTL8. In 2013 it was suggested by Melton and Yi from Harvard that ANGPTL8 promotes mouse pancreatic islet cell proliferation. These results led the authors to propose an alternative name for ANGPTL8, betatrophin. However, the link between ANGPTL8 and islet proliferation was quickly proven false by other researchers. In fact, in December 2016 the original paper by Melton and Yi was retracted, putting the link between ANGPTL8 and islets cells to rest. Nevertheless, the name betatrophin continues to be used. Given the homology of ANGPTL8 with ANGPTL4 and ANGPTL3, and considering that ANGPTL8 does not promote beta cell proliferation, the name betatrophin should be abandoned in favor of ANGPTL8.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide that activates melanocortin receptors. It is given by injection and was approved in the United States in 2019 for a specific low-desire diagnosis in premenopausal women. It is not a hormonal therapy.
Earlier approaches were largely hormonal or psychological in focus, whereas this compound acts on central melanocortin signalling. It is not a vasodilator and does not share the mechanism of phosphodiesterase inhibitors. Head-to-head comparative data are limited.
Placebo responses in desire trials are large, so the average drug-placebo separation is small. Reporting therefore relies on validated questionnaires with statistical ranges. Individual responses vary widely.
PT-141 was the development code used for bremelanotide during its preclinical and early clinical programme. The peptide is now generally referred to by its international nonproprietary name.