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 2026-03-07 and is reviewed periodically as new material appears.
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.
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.
| 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 |
Melanocortin receptors form a family of five G-protein-coupled proteins, labelled MC1R through MC5R, that respond to peptides derived from pro-opiomelanocortin. Alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone are the best-known endogenous ligands. The receptors are distributed differently across tissues, so a single agonist can produce effects in the brain, skin, adrenal gland and vasculature. This distribution explains why one peptide can influence both pigmentation and motivated behaviour.
Bremelanotide is a cyclic heptapeptide that binds several melanocortin receptors rather than one. In vitro assays report agonist activity at MC1R, MC3R, MC4R and MC5R, with MC4R generally treated as the subtype most relevant to sexual effects. MC4R is expressed in hypothalamic nuclei involved in appetite, energy balance and motivated behaviour, which provides a plausible route for central action. Selective MC4R agonists studied in animals produce comparable behavioural changes, supporting that interpretation.
Identity and purity are usually established with reversed-phase high-performance liquid chromatography combined with mass spectrometry. A gradient of water and acetonitrile containing trifluoroacetic acid is a common mobile phase, and ultraviolet detection near 214 nanometres responds to the peptide backbone. Mass spectrometry confirms the expected molecular mass and helps reveal truncation or oxidation products. Purity is reported as a peak-area percentage, a figure that depends on the wavelength and gradient used, so values from different laboratories are not always directly comparable. Peptide mapping and amino acid analysis provide additional confirmation when required.
Regulatory status varies by jurisdiction, where approved prescription products, compounded preparations and research-grade material are treated as distinct categories with different documentation requirements. Suppliers of research material commonly issue a certificate of analysis listing purity, identity and sometimes endotoxin content. Independent verification by a third-party laboratory is often recommended because self-reported figures are difficult to check. Literature discussions usually state the source, purity and storage conditions of the material used, since these details affect reproducibility. Analysts note that a reported purity figure does not by itself describe biological activity.
=== Gut and Brain === Signal peptide (1-20) Glicentin (21–89) Oxyntomodulin (OXY or OXM, 53–89) – A further cleavage of Glicentin Glucagon-like peptide 1 (GLP-1, 92–128) – first seven residues further cleaved Glucagon-like peptide 2 (GLP-2, 146–178)
With the advent of size exclusion chromatography (SEC), MALS measurements began to be used in conjunction with an on-line concentration detector to determine absolute molar mass and size of sample fractions eluting from the column, rather than depending on calibration techniques. These flow mode MALS measurements have been extended to other separation techniques such as field flow fractionation, ion exchange chromatography, and reversed-phase chromatography. The angular dependence of light scattering data is shown below in a figure of mix of polystyrene spheres which was separated by SEC. The two smallest samples (farthest to the right) eluted last and show no angular dependence. The sample, second to the right shows a linear angular variation with the intensity increasing at lower scattering angles. The largest sample, on the left, elutes first and shows non-linear angular variation.
Apart from X-ray crystallography, important analytical techniques for the characterization of metal carbonyls are infrared spectroscopy and 13C NMR spectroscopy. These two techniques provide structural information on two very different time scales. Infrared-active vibrational modes, such as CO-stretching vibrations, are often fast compared to intramolecular processes, whereas NMR transitions occur at lower frequencies and thus sample structures on a time scale that, it turns out, is comparable to the rate of intramolecular ligand exchange processes. NMR data provide information on "time-averaged structures", whereas IR is an instant "snapshot". Illustrative of the differing time scales, investigation of dicobalt octacarbonyl (Co2(CO)8) by means of infrared spectroscopy provides 13 νCO bands, far more than expected for a single compound. This complexity reflects the presence of isomers with and without bridging CO ligands. The 13C NMR spectrum of the same substance exhibits only a single signal at a chemical shift of 204 ppm. This simplicity indicates that the isomers quickly (on the NMR timescale) interconvert.
Sources: en.wikipedia.org
Octadecyltrichlorosilane (ODTS or n-octadecyltrichlorosilane) is an organosilicon compound with the formula CH3(CH2)17SiCl3. A colorless liquid, it is used as a silanization agent to prepare hydrophobic stationary phase, for reversed-phase chromatography. It is also evaluated for forming self-assembled monolayers on silicon dioxide substrates. Its structural chemical formula is CH3(CH2)17SiCl3. It is flammable and hydrolyzes readily with release of hydrogen chloride. Dodecyltrichlorosilane, an ODTS analog with shorter alkyl chain, is used for the same purpose. ODTS-PVP films are used in organic-substrate LCD displays.
== Disaccharide phosphorylases == Different biocatalytic approaches have been developed toward the synthesis of glycosides in past decades, for which glycosyltransferases and glycoside hydrolases are among the most common catalysts. The former often needs expensive materials and the latter often shows low yields. De Winter et al. investigated use of cellobiose phosphorylase (CP) toward synthesis of alpha-glycosides in ionic liquids. The best condition for use of CP was found to be in the presence of the ionic liquid AMMOENG 101 and ethyl acetate.
=== Pharmacodynamics === 3,4-DMA has been assessed in various biochemical and preclinical studies. Its affinity (Ki) for the rat serotonin 5-HT2A receptor has been assessed and was found to be 43,300 nM. For comparison, the affinity of para-methoxyamphetamine (PMA) was 33,600 nM, of 2,5-dimethoxyamphetamine (2,5-DMA) was 5,200 nM, and of 2,5-dimethoxy-4-methylamphetamine (DOM) was 100 nM in the same study. 3,4-DMA also showed affinity for the 5-HT1 receptor (Ki = 64,600 nM). The drug has additionally been found to be a monoamine oxidase inhibitor (MAOI), with an IC50Tooltip half-maximal inhibitory concentration of 20,000 nM for monoamine oxidase A (MAO-A), whereas it was inactive at monoamine oxidase B (MAO-B) (IC50 > 100,000 nM). 3,4-DMA does not produce hyperlocomotion and hence lacks stimulant-like effects in rodents. It also fails to produce stimulus generalization to dextroamphetamine in rodent drug discrimination tests, likewise suggesting that it lacks stimulant- or amphetamine-like effects. The drug partially but incompletely substituted for DOM in rodents, suggesting that it may lack psychedelic-like effects. 3,4-DMA partially to fully substituted for partially to fully substituted for PMMA, MDMA, and MDA in rodents, suggesting that it may have entactogen-like effects.
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.
Cold storage at minus twenty degrees Celsius or below is typical, with desiccant and protection from light. The solid form is far more stable than any solution.