The short version of HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-07-23. Anything still debated is marked as such rather than presented as settled.
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.
The compound emerged from a research programme examining melanocortin analogues for effects on skin pigmentation. During early human studies, participants reported spontaneous erections as an unexpected side effect, which redirected development toward sexual function rather than tanning. An intranasal formulation was investigated in clinical trials but did not reach market approval. A subcutaneous injectable version later completed the regulatory process, and the nasal route does not appear in approved labelling.
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.
Compared with melanotan II, bremelanotide is a smaller cyclic peptide with a more constrained backbone, which affects receptor selectivity and metabolic stability. Published descriptions give a plasma half-life on the order of a few hours after subcutaneous administration, with elimination through hepatic and renal routes and limited plasma protein binding. Central access is inferred from effects observed in animal models, although direct measurement in humans is limited. Handling and storage requirements follow from the peptide backbone, which is susceptible to hydrolysis and oxidation.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H68N14O10 | Cyclic heptapeptide backbone |
| Molecular mass | Approximately 1025 Da | Nominal mass of the free peptide |
| Appearance | White to off-white lyophilised powder | Typical for purified synthetic peptides |
| Solubility class | Freely soluble in water | Organic solubility is limited |
| Typical storage temperature | −20 °C or below | Protect from moisture and light |
PT-141 is the original development code for bremelanotide, a synthetic peptide first studied as a potential tanning and sexual-response agent in the 1990s. Researchers at a small American biotechnology firm designed it as a shortened analogue of melanotan II, which itself came from work on alpha-melanocyte-stimulating hormone. Early screening focused on pigmentation, but behavioural observations in animal models redirected attention toward sexual motivation. That shift made PT-141 one of the first melanocortin compounds investigated specifically for effects on desire rather than on skin colour.
Clinical development proceeded through two routes of administration. An intranasal formulation advanced first, but variable absorption and tolerability problems led to a switch to subcutaneous injection. The United States Food and Drug Administration approved the subcutaneous product in 2019 for hypoactive sexual desire disorder in premenopausal women. Marketing rights subsequently changed hands, and commercial availability has fluctuated since approval. Use in men, in postmenopausal women, and in combination with other agents remains outside the approved label.
Outside the approved product, bremelanotide circulates as a research chemical sold by peptide vendors, often labelled PT-141. Such material is not manufactured under pharmaceutical quality standards, and independent testing has repeatedly found content that differs from the label. Analytical certificates supplied with a purchase are not strong evidence of purity because they are usually generated by the seller. Online discussion tends to blur the distinction between the approved drug and unregulated powder, which complicates interpretation of reported experiences.
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.
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.
Whether the behavioral effect originates centrally, peripherally, or through both remains an active question. Animal experiments using receptor antagonists and site-specific injections point toward hypothalamic melanocortin circuits as a key locus, but translating those findings to humans is not straightforward. Blood pressure changes observed in trials suggest a vascular component that may be peripherally mediated. The relationship between receptor occupancy and reported effect has not been mapped in humans, and no validated biomarker predicts response. This gap makes it difficult to explain individual variability on pharmacological grounds alone.
Bremelanotide acts as an agonist at melanocortin receptors, a family of five G-protein-coupled receptors labeled MC1 through MC5. Binding studies indicate activity at several of these subtypes rather than strict selectivity for one. Signalling proceeds mainly through Gs-mediated activation of adenylyl cyclase, raising intracellular cyclic AMP. The MC4 receptor, expressed in hypothalamic and limbic circuits, is widely regarded as the subtype most relevant to sexual response. Because the molecule is not subtype-selective, effects at other melanocortin receptors are expected and are used to explain some observed side effects.
The peptide contains seven amino acids arranged in a ring, closed by a lactam bridge between a side-chain acid and an amine. This cyclic constraint holds the backbone in a defined conformation and increases resistance to enzymatic breakdown relative to linear analogs. N-terminal acetylation and a C-terminal amide further protect the molecule from exopeptidases. The result is a compound with a comparatively long circulation time for a small peptide. Structural modification of the bridge alters receptor affinity, which is one reason analogs in this family differ in their subtype preferences.
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.
Identity and purity are established with orthogonal methods rather than a single test. Reverse-phase high-performance liquid chromatography with ultraviolet detection gives a purity figure by area normalization, while mass spectrometry confirms the expected molecular ion. Amino acid analysis or peptide mapping can detect sequence errors that a mass value alone would miss, and residual counterion content is sometimes measured separately. Common impurities include truncated sequences, oxidized residues, and deamidated products; reporting them individually is more informative than a single composite purity number.
The catalytic hydrogenation of (S)-1-N-Cbz-prolinamide [34079-31-7] (1) gives L-Prolinamide [7531-52-4] (2). This is condensed with Z-His-NHNH2 [49706-31-2] (3) in the presence of nitrous acid to give Benzyloxycarbonyl-L-histidyl-L-prolineamide, PC13229382 (4). The protecting group is hydrolyzed in acid to give His-pro-amide [33605-69-5] (5). This is finally condensed with (3R,6R)-6-Methyl-5-oxothiomorpholine-3-carboxylic acid, PC99645792 (6) in the presence of by of 1-hydroxybenzotriazole and dicyclohexylcarbodiimide, completing the synthesis of Montirelin (7).
Hyperthyroidism is one of the most common endocrine conditions affecting older domesticated housecats. In the United States, up to 10% of cats over ten years old have hyperthyroidism. The disease has become significantly more common since the first reports of feline hyperthyroidism in the 1970s. The most common cause of hyperthyroidism in cats is the presence of benign tumors called adenomas. Adenomas cause 98% of cases, but the reason these cats develop such tumors remains under study. The most common presenting symptoms are: rapid weight loss, tachycardia (rapid heart rate), vomiting, diarrhea, increased consumption of fluids (polydipsia), increased appetite (polyphagia), and increased urine production (polyuria). Other symptoms include hyperactivity, possible aggression, an unkempt appearance, and large, thick claws. Heart murmurs and a gallop rhythm can develop due to secondary hypertrophic cardiomyopathy. About 70% of affected cats also have enlarged thyroid glands (goiter). The same three treatments used with humans are also options in treating feline hyperthyroidism (surgery, radioiodine treatment, and anti-thyroid drugs). There is also a special low-iodine diet available that will control symptoms, provided no other food is fed; Hill's y/d formula, when given exclusively, decreases T4 production by limiting the amount of iodine needed for thyroid hormone production. It is the only available commercial diet that focuses on managing feline hyperthyroidism.
=== CBRN equipment === Light Anti-Gas Respirator - Issued until the arrival of the S6 respirator. S6 NBC Respirator - Issued from 1966 S10 NBC Respirator - Issued from 1986 No. 1 Mk 1-4 Protective Suit
=== FTIR as detector in chromatography === The speed of FTIR allows spectra to be obtained from compounds as they are separated by a gas chromatograph. However this technique is little used compared to GC-MS (gas chromatography-mass spectrometry) which is more sensitive. The GC-IR method is particularly useful for identifying isomers, which by their nature have identical masses. Liquid chromatography fractions are more difficult because of the solvent present. One notable exception is to measure chain branching as a function of molecular size in polyethylene using gel permeation chromatography, which is possible using chlorinated solvents that have no absorption in the area in question.
Sources: en.wikipedia.org
The xenon pit is a phenomenon of excess neutron absorption through 135Xe buildup in the reactor after a reduction in power or a shutdown and is often managed by letting the 135Xe decay away to a level at which neutron flux can be safely controlled via control rods again. A nuclear reactor will also produce much smaller amounts of 135Cs from the nonradioactive fission product 133Cs by successive neutron capture to 134Cs and then 135Cs. The thermal neutron capture cross section and resonance integral of 135Cs are 8.3 ± 0.3 and 38.1 ± 2.6 barns respectively. Disposal of 135Cs by nuclear transmutation is difficult, because of the low cross section as well as because neutron irradiation of mixed-isotope fission caesium produces more 135Cs from stable 133Cs. In addition, the intense medium-term radioactivity of 137Cs makes handling of nuclear waste difficult.
== History == The US Food and Drug Administration (FDA) approved sotagliflozin based on evidence from two clinical trials of 11,806 total participants with heart failure or with type 2 diabetes, chronic kidney disease, and other cardiovascular risk factors. The trials were conducted at 322 sites in 32 countries (SOLOIST/NCT03521934) and 750 sites in 42 countries (SCORED/NCT03315143) primarily in Europe, South America, and North America. Both trials were used for primary determination of the benefits and side effects of the drug. The benefits and side effects of sotagliflozin were evaluated in the two clinical trials. In both trials, participants were randomly assigned to receive either sotagliflozin or placebo by mouth once a day. Neither the participants nor the healthcare providers knew which treatment was being given until after the trial was completed. The benefit of sotagliflozin was evaluated by measuring the number of predefined events (death from cardiovascular causes, need for hospitalization for heart failure, or urgent medical care visit for heart failure) occurring in the patient population receiving sotagliflozin versus placebo.
His military friend was quoted as saying that their unit was allegedly deployed to South Ossetia for the exercises, but suddenly the war broke out. On 26 August 2008, Drug dlya druga reported that one mother was told by her son on 6 August that his company would be sent to South Ossetia on 9 August. At 3 am on 8 August her son was sent to Tskhinvali, where he was wounded. On 27 August 2008, Vecherny Saransk reported that Yunir Bikkinyaev, contract soldier of 135th Regiment, stopped to answer the phone calls on 7 August and his parents were worried. He later acknowledged he did so not to frighten his family. On 28 August 2008, Gazeta Yuga published a report about Zalim Gegraev, a wounded soldier from 1st company of the peacemaking battalion, who fought in South Ossetia. Gegraev's mother said that her son had told her that he was going to Tskhinvali before the war started. She also said that he had been to South Ossetia previously and when he was there, his phone did not work. Then Zalim spoke to journalist: "We had been there to participate in military exercises for a month in those areas before this. They ended, however we were not withdrawn. Then the order came to move to Tskhinvali. On 8 August we were near the town and waited for further instructions. I didn't even think that I could see such thing..."
Sources: en.wikipedia.org
== Tissues distribution == Studies have reported that humans express FFAR3 in their: (a) enteroendocrine L cells and K cells of the intestines; (b) endothelium of blood vessels in the frontal cortex of the brain, pancreatic β-cells, and adipose. i.e., fat, tissue (but not in mouse adipose tissue); (c) the vascular endothelium of the myometrium, the epithelium of the amnion, chorion and placenta, and certain immune cells in these tissues of pregnant women; (d) the hippocampus of the brain; (e) sympathetic ganglia, i.e., autonomic ganglia of the sympathetic nervous system; (f) certain types of immune cells, i.e., blood monocytes (but not mouse monocytes), basophils, dendritic cells derived from human monocytes isolated from whole blood, and the tissues containing these blood cells, i.e., the bone marrow, spleen, lymph nodes, and thymus; and (g) alveolar macrophages, and macrophages in various other tissues; and (h) certain immortalised cell lines, i.e., MCF-7 breast cancer, HCT116 colorectal cancer, HEK293 embryonic kidney, U937 leukemic promonocyte, THP-1 leukemic monocyte, EoL-1 leukemic eosinophil, Jurcat leukemic T lymphocyte, MOLT-4 T lymphoblast leukemic, and HL60 acute myeloid leukemia cells (but only when the HL60 cells are pre-treated with phorbol 12-myristate 13-acetate to promote their cellular differentiation). As noted, the expression of FFAR3 in the cells and tissues of animals are not always the same as those in humans.
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Adverse human health effects have been associated with a compound. There is an established relationship between the positive and negative effect(s) of the compound. Emerging contaminants are those which have not previously been detected through water quality analysis, or have been found in small concentrations with uncertainty as to their effects. The risk they pose to human or environmental health is not fully understood.
Several different classification systems have been used to describe aortic dissections. One such classification is based on chronicity and labels aortic dissections as hyperacute (<24 hours duration), acute (2–7 days), subacute (8–30 days), and chronic (>30 days). The systems commonly in use are based on either the anatomy of the dissection or the duration of onset of symptoms before the presentation. The Stanford system is used more commonly now, as it is more attuned to the management of the patient.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide that acts as an agonist at melanocortin receptors. It is not a hormone replacement therapy and not a vasodilator in the usual clinical sense, although it does affect vascular tone. Chemically it belongs to the melanocortin analogue family.
PT-141 was the internal development code used during early research and it persists in older publications, conference abstracts, and informal listings. The code and the approved name refer to the same molecule. Its continued use reflects habit in the literature rather than any difference in substance.
No. The intranasal form was studied in trials but was never approved, and absorption through the nasal route varies considerably between individuals. Approved labelling covers a subcutaneous injection only. Any nasal product sold outside regulated channels falls outside verified manufacturing.
Reported activity is highest at MC4R, with lower potency at MC1R and MC3R. The MC4R interaction is generally treated as the most relevant to its central effects. Selectivity is not absolute, and activity across the family is dose-dependent.