The short version of melanocortin fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-30 and is reviewed periodically as new material appears.
The compound binds several melanocortin receptor subtypes rather than a single target, with the strongest functional activity reported at MC4R and measurable activity at MC1R, MC3R and MC5R. MC4R populations are dense in hypothalamic nuclei that integrate energy balance, autonomic tone and reproductive behaviour, which is the anatomical basis for the proposed pro-desire effect. Because binding is not subtype-selective, pigmentary and vascular effects accompany central activity. Improving subtype selectivity is an active area of analogue design. Direct causal mapping from receptor occupancy to reported desire change in humans is not fully established.
After subcutaneous dosing, peak plasma concentrations appear within roughly one hour, and elimination is fast, with a half-life on the order of a few hours. Degradation is mainly proteolytic, and at least one circulating fragment retains receptor activity, so parent-drug levels alone do not describe total exposure. Clearance does not depend heavily on hepatic cytochrome enzymes, which lowers the likelihood of common metabolic interaction routes. Data in renal or hepatic impairment are limited. Repeated dosing does not appear to produce marked accumulation given the short half-life.
Early research on PT-141 grew out of work on melanotan II, a related cyclic peptide studied for pigmentation. Investigators observed that centrally acting melanocortin agonists also influenced sexual behaviour in animal models, and the programme shifted toward that endpoint. A nasal formulation was evaluated in clinical trials but showed inconsistent absorption, and later studies used subcutaneous administration instead. Regulatory approval in the United States followed in 2019 for a defined population of premenopausal women with acquired, generalised hypoactive sexual desire disorder. That approval was specific to that group rather than a broad indication.
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.
| Property | Value | Notes |
|---|---|---|
| Primary target | MC4R | Highest reported functional activity |
| Peak plasma time | About 1 hour | Subcutaneous administration |
| Elimination half-life | A few hours | Active fragment may extend effect |
| Main clearance route | Proteolytic degradation | Not cytochrome-dependent |
| Typical assay | LC-MS/MS | Plasma quantification |
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.
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.
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.
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.
How receptor activation translates into a change in desire is not established in detail. Proposed steps include modulation of dopaminergic signalling in reward circuits and downstream effects on autonomic tone. Human data consist mainly of clinical trials measuring self-reported outcomes rather than direct measurements of brain activity or transmitter release. The transient rise in blood pressure sometimes observed after administration is likewise reported consistently but explained only partly by known melanocortin pathways.
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.
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.
A collection of spin-off novels written by Kana Akatsuki is available for free on the Kakuyomu website (Kadokawa Co. & Hatena Co.). Some spin-offs from the "Dance of Spring" arc have received a manga adaptation in the spin-off Agents of the Four Seasons: One Hundred Songs and One Hundred Pages (春夏秋冬代行者 百歌百葉, Shunkashūtō Daikōsha Hyakka Hyakuyō).
Following subcutaneous injection, albiglutide reaches highest blood concentrations after three to five days. Steady-state concentrations are achieved after three to five weeks. The substance is most likely broken down by protease enzymes to small peptides and amino acids. Being resistant to dipeptidyl peptidase-4 (DPP-4), the enzyme that breaks down GLP-1, albiglutide has a biological half-life of five (4–7) days, which is considerably longer than the older GLP-1 analogs exenatide and liraglutide. This allows for a once-weekly administration, unlike liraglutide but like the extended-release form of exenatide. Albiglutide is a peptide consisting of 645 proteinogenic amino acids with 17 disulfide bridges. Amino acids 1–30 and 31–60 constitute two copies of modified human GLP-1, the alanine at position 2 having been exchanged for a glycine for better DPP-4 resistance. The remaining sequence is human albumin. The complete sequence is
Secobarbital/brallobarbital/hydroxyzine was a combination tablet containing 50 mg brallobarbital, 150 mg secobarbital and 50 mg hydroxyzine that was used as a sedative. It was sold under the brand name Vesparax. This drug has been withdrawn from the market in most countries. Hydroxyzine and secobarbital lengthen the half-life of brallobarbital. Because of this long half-life, it has symptoms resembling a hangover on the next day. Jimi Hendrix was under the influence of Vesparax when he died of asphyxia due to aspiration of vomit on 18 September 1970.
The first performance in Los Angeles in 1954 was introduced with a tribute to Thomas from Aldous Huxley. Thomas spent the last nine or ten days of his third tour in New York mostly in the company of Reitell, with whom he had an affair. During this time, Thomas fractured his arm falling down a flight of stairs when drunk. Reitell's doctor, Milton Feltenstein, put his arm in plaster and treated him for gout and gastritis. After returning home, Thomas worked on Under Milk Wood in Laugharne. Aeronwy, his daughter, noticed that his health had "visibly deteriorated...I could hear his racking cough. Every morning he had a prolonged coughing attack...The coughing was nothing new but it seemed worse than before." She also noted that the blackouts that Thomas was experiencing were "a constant source of comment" amongst his Laugharne friends. Thomas sent the original manuscript to Douglas Cleverdon on 15 October 1953. It was copied and returned to Thomas, who lost it in a pub in London and required a duplicate to take to America. Thomas flew to the States on 19 October 1953 for what would be his final tour. He died in New York before the BBC could record Under Milk Wood. Richard Burton starred in the first broadcast in 1954, and was joined by Elizabeth Taylor in a subsequent film. In 1954, the play won the Prix Italia for literary or dramatic programmes.
Sources: en.wikipedia.org
=== Nile red === Nile red (also known as Nile blue oxazone) is formed by boiling Nile blue with sulfuric acid. This produces a mix of Nile red and Nile blue. Nile red is a lipophilic stain; it will accumulate in lipid globules inside cells, staining them red. Nile red can be used with living cells. It fluoresces strongly when partitioned into lipids, but practically not at all in aqueous solution.
=== Wild birds and fish === Thiamine deficiency has been identified as the cause of a paralytic disease affecting wild birds in the Baltic Sea area dating back to 1982. In this condition, there is difficulty in keeping the wings folded along the side of the body when resting, loss of the ability to fly and voice, with eventual paralysis of the wings and legs and death. It affects primarily 0.5–1 kg-sized birds such as the European herring gull (Larus argentatus), common starling (Sturnus vulgaris), and common eider (Somateria mollissima). Researchers noted, "Because the investigated species occupy a wide range of ecological niches and positions in the food web, we are open to the possibility that other animal classes may develop thiamine deficiency, as well."p. 12006 In the counties of Blekinge and Skåne, mass deaths of several bird species, especially the European herring gull, have been observed since the early 2000s. More recently, species of other classes seems to be affected. High mortality of salmon (Salmo salar) in the river Mörrumsån is reported, and mammals such as the Eurasian elk (Alces alces) have died in unusually high numbers. Lack of thiamine is the common denominator where analysis is done. In April 2012, the County Administrative Board of Blekinge found the situation so alarming that they asked the Swedish government to set up a closer investigation.
=== Sports journalists === Jeremy Gaige (1951), chess archivist and journalist Paul Zimmerman (1955), football writer for Sports Illustrated known as "Dr. Z" Robert Lipsyte (1957), sports writer for The New York Times, correspondent for ABC News and host of The Eleventh Hour Chet Forte (1957), first director of Monday Night Football Steven Krasner (1975), sports journalist famous for covering the Boston Red Sox for The Providence Journal 1986–2008 Bob Klapisch (1979), sports writer for The Record and Fox Sports Gary Cohen (1981), television play-by-play announcer for the New York Mets
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The Dirty Drug and the Ice Cream Tub Radiolab episode on the discovery of rapamycin Clinical trial number NCT02494570 for "A Phase 2 Study of ABI-009 in Patients With Advanced Malignant PEComa (AMPECT)" at ClinicalTrials.gov
== Synthesis and structure == With the formula Zn[(S2P(OR)2]2, zinc dithiophosphate features diverse R groups. Typically, R is a branched or linear alkyl between 1-14 carbons in length. Examples include 2-butyl, pentyl, hexyl, 1,3-dimethylbutyl, heptyl, octyl, isooctyl (2-ethylhexyl), 6-methylheptyl, 1-methylpropyl, dodecylphenyl, and others. A list of examples with their CAS numbers is here. Zinc dithiophosphate are often produced in two steps. First phosphorus pentasulfide is heated with suitable alcohols (ROH) to give the dithiophosphoric acid. A wide variety of alcohols can be employed, which allows the lipophilicity of the final zinc product to be fine tuned. The resulting dithiophosphoric acid is then neutralized, e.g., with ammonia or by adding zinc oxide:
The state prosecuted the accused as Marxist revolutionaries seeking to establish a Soviet-backed regime in South West Africa. In what became known as the "1967 Terrorist Trial", six of the accused were found guilty of committing violence in the act of insurrection, with the remainder convicted for armed intimidation, or having received military training for the purpose of insurrection. During the trial, the defendants unsuccessfully argued against allegations that they were privy to an external communist plot. All but three received sentences ranging from five years to life imprisonment on Robben Island.
careful modeling to anticipate the effect that an immunization campaign will have on the epidemiology of the disease in the medium to long term ongoing surveillance for the relevant disease following introduction of a new vaccine maintenance of high immunization rates, even when a disease has become rare
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MC4R is regarded as the primary mediator on the basis of binding and functional assays. Other subtypes are also engaged, which helps explain flushing and related side effects. The step from receptor activation to reported desire change remains partly inferential.
Elimination is rapid, with a half-life of a few hours. An active fragment circulates after breakdown, so biological activity may outlast measurable parent drug. This is one reason single-timepoint measurements are limited.
Because breakdown is mainly proteolytic rather than cytochrome-dependent, classic metabolic interactions are less likely. Agents affecting blood pressure could still matter. Formal interaction studies are sparse.
PT-141 was the development code used for bremelanotide during its preclinical and early clinical programme. The peptide is now generally referred to by its international nonproprietary name.