The short version of bremelanotide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
Identity and purity testing for this peptide typically relies on reversed-phase high-performance liquid chromatography with ultraviolet detection, reported as area-percent purity. Mass spectrometry, usually in tandem mode, confirms molecular mass and supports quantification in biological matrices. Sequence confirmation may use peptide mapping after enzymatic digestion, while nuclear magnetic resonance and circular dichroism supply supplementary structural detail. No single technique establishes identity alone, so laboratories compare retention time, mass, and fragment pattern against a verified reference standard.
The lactam ring that closes the peptide backbone improves resistance to exopeptidase attack, but the molecule stays susceptible to hydrolysis and oxidation once dissolved. Degradation accelerates with temperature, extreme pH, and light exposure, and repeated freeze-thaw cycles promote aggregation and material loss. Lyophilized powder held desiccated at or below minus twenty degrees Celsius is the common way to keep reference material. Reconstituted solutions are generally kept cold and used within a short window because their stability is far lower than that of the dry solid.
| 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 |
Reverse-phase high-performance liquid chromatography is the standard method for assessing purity. Mass spectrometry confirms molecular identity and detects sequence variants or truncation products. Ultraviolet absorbance at 214 or 280 nm is used for quantification, with the choice depending on the peptide sequence. Method validation typically addresses linearity, limit of detection, and precision across a defined concentration range. Impurity profiling may also employ ion-exchange or size-exclusion chromatography, and these techniques complement one another.
Certificate of analysis documents usually report purity percentage, molecular weight, and appearance. Researchers verify identity by comparing observed and theoretical mass values. Chain-of-custody records and batch numbers help trace material from source to experiment. Independent verification of supplier claims is considered good practice when material identity is critical to a study. Records should include the storage history of each aliquot, and unexpected deviations in appearance or solubility warrant re-testing before use.
=== Homoleptic complexes (only amino acid ligands) === Mixing simple metal salts with solutions of amino acids near neutral or elevated pH often affords bis- or tris complexes. For metal ions that prefer octahedral coordination, these complexes often adopt the stoichiometry M(aa)3 (aa = amino carboxylate, such as glycinate, H2NCH2CO2−). Complexes of the 3:1 stoichiometry have the formula [M(O2CC(R)HNH2)3]z. Such complexes adopt octahedral coordination geometry. These complexes can exist in facial and meridional isomers, both of which are chiral. The stereochemical possibilities increase when the amino acid ligands are not homochiral. Both the violet meridional and red-pink facial isomers of tris(glycinato)cobalt(III) have been characterized With L-alanine, L-leucine, and other amino acids, one obtains four stereoisomers. With cysteine, the amino acid binds through N and thiolate. Complexes with the 2:1 stoichiometry are illustrated by copper(II) glycinate [Cu(O2CC(R)HNH2)2], which akso exists as a pentacoordinate monohydrate. When the metal is square planar, these complexes can exist as cis and trans isomers. The stereochemical possibilities increase when the amino acid ligands are not homochiral. Homoleptic complexes are also known where the amino carboxylate is tridentate amino acids. One such complex is Ni(κ3-histidinate)2.
Therefore, while the electronic placement of hydrogen in group 1 predominates, some rarer arrangements show either hydrogen in group 17, duplicate hydrogen in both groups 1 and 17, or float it separately from all groups. This last option has nonetheless been criticized by the chemist and philosopher of science Eric Scerri on the grounds that it appears to imply that hydrogen is above the periodic law altogether, unlike all the other elements. Helium is the only element that routinely occupies a position in the periodic table that is not consistent with its electronic structure. It has two electrons in its outermost shell, whereas the other noble gases have eight; and it is an s-block element, whereas all other noble gases are p-block elements. However it is unreactive at standard conditions, and has a full outer shell: these properties are like the noble gases in group 18, but not at all like the reactive alkaline earth metals of group 2. For these reasons helium is nearly universally placed in group 18 which its properties best match; a proposal to move helium to group 2 was rejected by IUPAC in 1988 for these reasons. Nonetheless, helium is still occasionally placed in group 2 today, and some of its physical and chemical properties are closer to the group 2 elements and support the electronic placement. Solid helium crystallises in a hexagonal close-packed structure, which matches beryllium and magnesium in group 2, but not the other noble gases in group 18.
The frog's brands were healed and readable within 24 hours of application, making this method nearly immediately effective as a tracking system. The branded area gradually loses its pigmentation such that older brands become almost completely transparent, increasing their legibility over time.
Sources: en.wikipedia.org
They were offered in three shapes (narrow neck, wide mouth, and flat) and multiple sizes, for a total of ten varieties. By 1925, the product line had been limited to a small subset of the original shapes and sizes. In the 1950s an upright Pyrex bottle with a narrow neck was introduced. In the 1960s a wide-neck version was finally introduced to the UK market. The design of upright bottles with a wider mouth meant that they could be more easily cleaned, and sterilized in batches. Soft nipples of various materials were introduced early in the history of feeding (e.g., leather, cork, sponge, dried cow's teat filled with cloth). Many were very difficult to clean and when unsanitary could pose a serious threat to infant health. Although Elijah Pratt of New York patented the first rubber nipple in 1845, it took until the 20th century before materials and technology improved sufficiently to allow manufacture of a soft nipple that was practical for use. The invention of rubber (1840s) provided a material that was soft. Early black Indian rubber "had a very strong pungent smell", and did not survive repeated exposures to hot water. However, by the early 1900s more pleasing rubber nipples could be manufactured in volume and could withstand the heat of sterilization. During the 1940s nurse Adda M. Allen filed for multiple patents relating to the design of baby bottles, including the first disposable collapsible liner for a baby bottle. Her patent was one of many attempts to design a bottle to limit swallowing of air during feeding, and reduce gastric upset and spitting up.
== Cause == Schwartz–Jampel syndrome is caused by mutations in the HSPG2 gene, which makes the protein perlecan, which is found in muscle and cartilage. Relationships between the disease and perlecan deficiency have been studied. In Schwartz–Jampel syndrome, it is suspected that abnormal perlecan function leads to a deficiency in acetylcholinesterase, an enzyme involved in breaking down the neurotransmitter acetylcholine, which incites muscle contraction. If acetylcholine is not broken down, it can lead to prolonged muscle contraction/stiffening of the muscles (myotonia). The condition is believed to follow an autosomal recessive inheritance pattern, although some reported cases suggest an autosomal dominant inheritance pattern.
The Centre Party, whose pragmatic principles generally left it open to supporting either a monarchical or republican form of government, proved one of the mainstays of the Weimar Republic, continuing the cooperation with SPD and DDP in the Weimar Coalition. This combination, however, lost its majority in the 1920 elections. The formation of the new Christian People's Party in Rhineland (May 1920) caused considerable concern among the Centre leadership. Seeing the exodus of conservative Catholics caused by a sharp left turn of the Centre at the end of war, Adam Stegerwald proposed his "Essen program" (September 1920) that promised Germany to become "Christian, democratic, German, and social" and a plan to form a broad-based Christian party. The party was an ideologically diverse coalition of Catholic politicians, comprising republicans like Matthias Erzberger and Joseph Wirth as well as right-wingers like Franz von Papen. As a result of the party's flexibility, it participated in every government between 1919 and 1932, both with parties to their left and to their right. The Centre mainly provided the ministers for finance and labour and, on four occasions, the Chancellor. However, this also damaged the party's prospects because it was increasingly associated with all of the conflicts, problems, and failures of the Republic.
== Fertilisation == Most notably, oxidative burst post fertilisation can be seen in the sea urchin egg. This is believed to be evolutionally divergent from that in neutrophils. Hydrogen peroxide is produced by egg oxidase activity following an increase in oxygen consumption. This is essential for the cross-linking of the ovum proteins to prevent lethal polyspermy. Hydrogen peroxide itself is also spermicidal. However, the generated reactive species are maintained at lower levels than in immunity to protect the fertilised egg itself from oxidative damage. This is achieved by the elimination of hydrogen peroxide primarily through the dual function of the same egg oxidase, and secondarily through cytoplasmic ROS scavengers, such as catalase and glutathione.
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.
Chemical degradation such as hydrolysis and oxidation proceeds more slowly as temperature falls. Cold storage also limits microbial growth in reconstituted material. Repeated warming should be avoided because thermal cycling stresses the peptide.