The short version of lyophilisation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-29 and is reviewed periodically as new material appears.
Development began with intranasal formulations investigated for erectile dysfunction, but blood pressure elevation limited that route and prompted a switch to subcutaneous delivery. Clinical testing then shifted toward hypoactive sexual desire disorder in premenopausal women, and a subcutaneous product received United States approval in 2019. Later trials examined other populations with mixed results, and questions about effect size, durability and patient selection remain open in the peer-reviewed literature. Research interest continues in parallel with the broader melanocortin field, where several synthetic analogues are studied together.
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.
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.
Lyophilized peptide material is generally stored at -20 °C or below to limit degradation, while reconstituted solutions are less stable and are typically kept refrigerated and protected from light. Repeated freeze-thaw cycles can accelerate aggregation and should be minimized. Stability for any specific lot depends on purity, moisture content, and packaging. Handling in a temperature-controlled environment reduces variability across replicates, and exposure to ambient humidity during weighing can introduce error. Aliquotting reduces the number of times a stock container is opened.
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.
| Property | Value | Notes |
|---|---|---|
| Research code | PT-141 | Used in early literature before the generic name became common |
| Generic name | Bremelanotide | International nonproprietary name |
| Peptide class | Cyclic heptapeptide | Seven residues joined by a lactam bridge |
| Primary receptor | MC4R | Lower affinity reported at MC1R, MC3R and MC5R |
| Route studied clinically | Subcutaneous injection | Intranasal route was abandoned after pressor effects |
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.
Lyophilised peptide is generally held below minus twenty degrees Celsius, protected from light and moisture, because hydrolysis and oxidation accumulate faster at ambient temperature. Once reconstituted, solutions are typically kept between two and eight degrees Celsius and used within a short window defined by the supplier. Repeated freeze-thaw cycles are avoided since they promote aggregation and loss of soluble material. Container material matters as well, because peptides adsorb to certain plastics and glass surfaces at low concentration. Stability figures supplied by a vendor apply only to the specific lot and buffer that were tested.
Bremelanotide acts as a non-selective agonist at melanocortin receptors, with reported activity at MC1R, MC3R, MC4R and MC5R. The proposed basis for its central effects is activation of MC4R populations in the hypothalamus, a region associated with appetite and reproductive signalling. Because the peptide carries a net positive charge and polar side chains, it does not cross biological membranes freely, which is one reason oral administration is not the standard route. Effects generally appear within an hour of parenteral administration and are described as centrally mediated rather than peripheral.
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.
Approved use is narrow and jurisdiction-specific. In the United States, the injectable product is authorised for premenopausal women with acquired, generalised hypoactive sexual desire disorder, a diagnosis that requires documented distress. It is not approved for men, for postmenopausal women, or for use alongside hormonal contraceptives under the approved labelling. Outside regulated markets, the same peptide is frequently sold as a research chemical, where identity, purity, and sterility are not independently verified.
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.
== External links == History of Discovery: The Tissue-Type Plasminogen Activator Story, Collen, D., Lijnen, H.R. Genentech Press Release 1982 Archived 2018-09-13 at the Wayback Machine Tissue Plasminogen Activator from the American Heart Association Widening the Window : Strategies to buy time in treating ischemic stroke - Scientific American (August 2005) Study expands window for effective stroke treatment - explained on YouTube
=== Other methods and techniques === Prior to RSKSOP-175, the EPA used Method 3810 (1986), which before that was Method 5020. However, Method 3810 is still used by some laboratories. Other headspace GC methods include:
== Interactions == EMP has been reported to increase the efficacy and toxicity of tricyclic antidepressants like amitriptyline and imipramine. When products containing calcium, aluminium, and/or magnesium, such as dairy products like milk, various foods dietary supplements, and antacids, are consumed concomitantly with EMP, an insoluble chelate complex/phosphate salt between EMP and these metals can be formed, and this can markedly impair the absorption and hence oral bioavailability of EMP. There may be an increased risk of angioedema in those concurrently taking ACE inhibitors.
Congenital dysfibrinogenemia is a rare autosomal dominant inherited disorder in which plasma fibrinogen is composed of a dysfunctional fibrinogen made by a mutated FGA, FGB, or FBG gene inherited from one parent plus a normal fibrinogen made by a normal gene inherited from the other parent. As a reflection of this duality, plasma fibrinogen levels measured by immunological methods are normal (>150 mg/dl) but are c. 50% lower when measured by clot formation methods. The disorder exhibits reduced penetrance, with only some individuals with the abnormal gene showing symptoms of abnormal bleeding and thrombosis.
=== Cancer === Specific SNPs are associated with an elevated risk of lung cancer and interact with folate dietary intake in this etiology. The (MTRR):c.66A>G mutation relates to a significant increase in the risk of lung cancer. When co-expressed with the polymorphism (MTR): 2756A>G, lung cancer risk is further increased in a dose dependent manner. Correlation between this polymorphism and increased risk of lung cancer is present with low folate intake and high vitamin B12, suggesting a B12 independent mechanism of action. This mutation is also associated with an increased risk in colorectal cancer, acute lymphoblastic leukemia, bladder cancer, cervical intraepithelial neoplasia, non-Hodgkin lymphoma and esophageal squamous cell carcinoma.
Sources: en.wikipedia.org
By the terms of the 1945 Potsdam Agreement signed by the three victorious Great Powers, the Soviet Union retained most of the territories captured as a result of the Molotov–Ribbentrop Pact of 1939, including western Ukraine and western Belarus, and gained others. Lithuania and the Königsberg area of East Prussia were officially incorporated into the Soviet Union, in the case of the former without the recognition of the Western powers. Poland was compensated with the bulk of Silesia, including Breslau (Wrocław) and Grünberg (Zielona Góra), the bulk of Pomerania, including Stettin (Szczecin), and the greater southern portion of the former East Prussia, along with Danzig (Gdańsk), pending a final peace conference with Germany which eventually never took place. Collectively referred to by the Polish authorities as the "Recovered Territories", they were included in the reconstituted Polish state. With Germany's defeat Poland was thus shifted west in relation to its prewar location, to the area between the Oder–Neisse and Curzon lines, which resulted in a country more compact and with much broader access to the sea.[c] The Poles lost 70% of their pre-war oil capacity to the Soviets, but gained from the Germans a highly developed industrial base and infrastructure that made a diversified industrial economy possible for the first time in Polish history. The flight and expulsion of Germans from what was eastern Germany prior to the war began before and during the Soviet conquest of those regions from the Nazis, and the process continued in the years immediately after the war.
=== Canada === Under Canadian regulations (C.R.C., c.870, section B.02.90), any product labelled, advertised, or sold as tequila must be manufactured in Mexico, as it would be for consumption in Mexico. Once imported to Canada for sale, it is legal for tequila to be diluted with distilled or otherwise purified water to adjust it to the desired strength and then sold.
The severity of chronic kidney disease (CKD) is described by six stages; the most severe three are defined by the MDRD-eGFR value, and first three also depend on whether there is other evidence of kidney disease (e.g., proteinuria):
In March 2009, the Obama administration cleared the US$2.1 billion sale of eight P-8 Poseidons to India. This deal, and the $5 billion agreement to provide Boeing C-17 military transport aircraft and General Electric F414 engines announced during Obama's November 2010 visit, made the US one of the top three military suppliers to India (after Israel and Russia). US Chairman of the Joint Chiefs of Staff Mike Mullen encouraged stronger military ties between the two nations, and said that "India has emerged as an increasingly important strategic partner [of the US]". US Undersecretary of State William J. Burns also said, "Never has there been a moment when India and America mattered more to each other." The Deputy Secretary of Defense, Ashton Carter, during his address to the Asia Society in New York City on August 1, 2012, said that India–US relationship has a global scope, in terms of the reach and influence of both countries. He also said that both countries are strengthening the relations between their defense and research organizations.
Sources: en.wikipedia.org
The code designates bremelanotide, a cyclic heptapeptide melanocortin receptor agonist. It served as an internal research identifier before the compound entered formal clinical development. The code and the generic name refer to the same molecule.
MC4R is generally described as the principal target, based on binding affinity and functional assays. Activity at MC1R, MC3R and MC5R is reported as weaker. Receptor selectivity is one reason the compound was pursued for central rather than vascular effects.
Both are synthetic melanocortin analogues built on a similar cyclic peptide scaffold. Bremelanotide is described in the literature as a metabolite-derived analogue of melanotan II rather than the same substance. The two differ in terminal modifications, which affect half-life and receptor profile.
Storage at -20 °C or below is standard for long-term stability. Desiccant and sealed containers limit moisture exposure. Solutions are prepared only when needed.