PT-141 comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-06-06. 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.
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.
== History == Heparin was discovered by Jay McLean and William Henry Howell in 1916, although it did not enter clinical trials until 1935. It was originally isolated from dog liver cells, hence its name (ἧπαρ hēpar is Greek for 'liver'; hepar + -in). McLean was a second-year medical student at Johns Hopkins University, and was working under the guidance of Howell investigating pro-coagulant preparations when he isolated a fat-soluble phosphatide anticoagulant in canine liver tissue. In 1918, Howell coined the term 'heparin' for this type of fat-soluble anticoagulant. In the early 1920s, Howell isolated a water-soluble polysaccharide anticoagulant, which he also termed 'heparin', although it was different from the previously discovered phosphatide preparations. McLean's work as a surgeon probably changed the focus of the Howell group to look for anticoagulants, which eventually led to the polysaccharide discovery. It had at first been accepted that it was Howell who discovered heparin. However, in the 1940s, Jay McLean became unhappy that he had not received appropriate recognition for what he saw as his discovery. Though relatively discreet about his claim and not wanting to upset his former chief, he gave lectures and wrote letters claiming that the discovery was his. This gradually became accepted as fact, and indeed after he died in 1959, his obituary credited him as being the true discoverer of heparin.
=== Protecting groups === As a class, esters serve as protecting groups for carboxylic acids. Protecting a carboxylic acid is useful in peptide synthesis, to prevent self-reactions of the bifunctional amino acids. Methyl and ethyl esters are commonly available for many amino acids; the t-butyl ester tends to be more expensive. However, t-butyl esters are particularly useful because, under strongly acidic conditions, the t-butyl esters undergo elimination to give the carboxylic acid and isobutylene, simplifying work-up.
==== Buspirone ==== Buspirone (Buspar) is a 5-HT1A receptor agonist used to treat generalized anxiety disorder. If an individual has only recently stopped taking benzodiazepines, buspirone will be less effective.
Sources: en.wikipedia.org
Analysis of the Y chromosome (father-inherited) likewise found no clear geographic structure, consistent with recent fragmentation. Datings by the 2024 study coincide with the penultimate glaciation, which may have restricted cross-oceanic movements through sea level fall. Separation probably remains enforced by thermal barriers, namely the cold Benguela upwelling separating South Africa from the Atlantic (which is known to deter white sharks) and the warm equatorial waters separating the North and South Pacific (a known soft barrier for many sharks and rays).
== Selected publications == Tiwari, V. Jin, Byungchang; Sun, Olivia; LopezGonzalez, Edwin D. J.; Chen, Min-Hsuan; Wu, Xiwei; Shah, Hardik; Zhang, Andrew; Herman, Mark A.; Spracklen, Cassandra N.; Goodman, Russell P.; Brenner, Charles (November 2025). "Glycerol-3-phosphate activates ChREBP, FGF21 transcription and lipogenesis in citrin deficiency". Nature Metabolism. 7 (11): 2284–2299. doi:10.1038/s42255-025-01399-3. ISSN 2522-5812. PMC 12638245 Brenner, C (2022-09-22). "Sirtuins are not conserved longevity genes". Life Metabolism (2): 122–133. doi:10.1093/lifemeta/loac025. ISSN 2755-0230. PMC 10081735. PMID 37035412. Brenner, C (January 2022). "Viral infection as an NAD+ battlefield". Nature Metabolism. 4 (1): 2–3. doi:10.1038/s42255-021-00507-3. ISSN 2522-5812. PMC 10155260. PMID 34980922. S2CID 245654307. Heer, CD; Sanderson, DJ; Voth, LS; Alhammad, YMO; Schmidt, MS; Trammell, SAJ; Perlman, S; Cohen, MS; Fehr, AR; Brenner, C (2020-10-13). "Coronavirus infection and PARP expression dysregulate the NAD Metabolome: an actionable component of innate immunity". Journal of Biological Chemistry. 295 (52): 17986–17996. doi:10.1074/jbc.RA120.015138. PMC 7834058. PMID 33051211. Vaur, P; Brugg, B; Mericskay, M; Li, Z; Schmidt, M S.; Vivien, D; Orset, C; Jacotot, E; Brenner, C (December 2017). "Nicotinamide riboside, a form of vitamin B3, protects against excitotoxicity-induced axonal degeneration". FASEB Journal. 31 (12): 5440–5452. doi:10.1096/fj.201700221RR. ISSN 1530-6860. PMID 28842432.
Some of the protesters attempted to burn down the building that housed the district committee of the PCR. The Securitate responded with tear gas and water cannons, while police beat up rioters and arrested many of them. Around 21:00 the rioters withdrew. They regrouped eventually around the Timișoara Orthodox Cathedral and started a protest march around the city, but again they were confronted by the security forces.
Carbohydrates – ranging from monosaccharides to polysaccharides and including blood group antigens, hyaluronic acid oligomers and sialic acid residues Peptide/protein – ranging from single amino acids to proteins as large as antibodies Labels – including fluorophores, radioisotopes, biotin, etc. Other – chemical moieties such as maleimide, click residues, PEG, charged compounds Note 1: Multimeric – the presentation of the F residue can be as multimers with controlled spacing and be variable. Note 2: Mass – the mass that can be anchored by an FSL Kode constructs can range from 200 to >1 million Da
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.