melanocortin agonist 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.
Updated 2026-04-12. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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 |
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.
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.
Development of the peptide passed through several delivery formats, including an intranasal version tested in early trials and an injectable version that entered later clinical study. Regulatory approval for a subcutaneous product in the United States was granted in 2019 after review of controlled trials in premenopausal women. Outside the clinic, the compound circulates in research and non-pharmaceutical markets under its code name, where identity and purity vary considerably between suppliers. Synonyms appearing across technical literature include bremelanotide, PT-141, and Palatin 141.
PT-141 is the research designation for bremelanotide, a synthetic cyclic heptapeptide developed as a melanocortin receptor agonist. The peptide contains seven amino acids with an internal lactam bridge that constrains the backbone into a stable ring. Cyclisation of this kind improves resistance to enzymatic degradation relative to linear analogues. The compound was first explored for effects on melanin production, because several melanocortin receptors influence pigmentation. Its later association with sexual desire emerged from observations made during that early work, and the molecule became the subject of a separate development programme.
Bremelanotide is a moderately large peptide with a molecular mass near 1025 daltons. In lyophilised form it appears as a white to off-white powder and is freely soluble in water and other polar solvents. The intact lactam ring is essential for receptor affinity, while linearised fragments bind far more weakly. Solutions are sensitive to extremes of pH and to prolonged exposure to light and heat, so handling typically involves buffered conditions and cold storage. Its short plasma half-life reflects rapid distribution and clearance rather than chemical breakdown inside the vial.
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.
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.
Some military officers involved in the Revers Report scandal (Rapport Revers) such as Salan were pessimistic about the way the war was being conducted, with multiple political-military scandals all happening during the war, starting with the Generals' Affair (Affaire des Généraux) from September 1949 to November 1950. As a result, General Georges Revers was dismissed in December 1949 and socialist Defense Ministry Jules Moch (SFIO) was brought on court by the National Assembly on November 28, 1950. The scandal started the commercial success of the first French news magazine, L'Express, created in 1953. The third scandal was financial-political, concerning military corruption, money and arms trading involving both the French Union army and the Việt Minh, known as the Piastres affair. By 1954, despite official propaganda presenting the war as a "crusade against communism", the war in Indochina was still growing unpopular with the French public. The political stagnation in the Fourth Republic meant that France was unable to extract itself from the conflict. Unlikely alliances had to be made between left- and right-wing parties in order to form a government invested by the National Assembly, resulting in parliamentary instability, with 14 prime ministers in succession between 1947 and 1954. The rapid turnover of governments (there were 17 different governments during the war) left France unable to prosecute the war with any consistent policy, according to veteran General René de Biré (who was a lieutenant at Dien Bien Phu).
=== Cyclic mechanical reinforcement === Most catch bonds were demonstrated using force-clamp force spectroscopy where upon initial ramping, a constant force is loaded on the bond to observe how long the bond lasts, i.e., measuring the bond lifetime at a constant force. Catch bonds are revealed when the mean bond lifetime (reciprocally related to the rate of bond dissociation) increases with the clamped force. Zhu and colleagues demonstrated that bond lifetime measured at the force-clamp phase could be substantially prolonged if the initial ramping included two forms of pre-conditioning: 1) loading the bond by ramping the force to a high level (peak force) before clamping the force at a low level for lifetime measurement, and 2) loading and unloading the bond repeatedly by multiple force cycles before clamping the force at a peak value for lifetime measurement. This new bond type, termed cyclic mechanical reinforcement (CMR), is distinct from catch bond, but it nevertheless resembles catch bond in that the bond lifetime increases with the peak force and with the number of cycles used to pre-condition the bond. CMR has been observed for interactions between integrin alpha 5 beta 1 and fibronectin and between G-actin and G-actin or F-actin.
=== Purity determination (w/w NMR) === While NMR is primarily used for structural determination, it can also be used for purity determination, provided that the structure and molecular weight of the compound is known. This technique requires the use of an internal standard of known purity. Typically this standard will have a high molecular weight to facilitate accurate weighing, but relatively few protons so as to give a clear peak for later integration e.g. 1,2,4,5-tetrachloro-3-nitrobenzene. Accurately weighed portions of the standard and sample are combined and analysed by NMR. Suitable peaks from both compounds are selected and the purity of the sample is determined via the following equation.
=== Distribution === Following absorption, 2,6-DCBQ distributes predominantly to highly perfused organs, such as the liver and the kidneys. Its moderate lipophilicity facilitates the crossing of cellular membranes. The quinone structure allows for redox cycling between quinone and hydroquinone within tissues. This process can lead to the formation of reactive oxygen species (ROS), contributing to intracellular oxidative stress. Due to its high reactivity and its metabolic transformation, 2,6-DCBQ does not significantly accumulate in adipose tissue.
== Compensated pathogenic deviations == Compensated pathogenic deviations refer to amino acid residues in a protein sequence that are pathogenic in one species but are wild type residues in the functionally equivalent protein in another species. Although the amino acid residue is pathogenic in the first species, it is not so in the second species because its pathogenicity is compensated by one or more amino acid substitutions in the second species. The compensatory mutation can occur in the same protein or in another protein with which it interacts. It is critical to understand the effects of compensatory mutations in the context of fixed deleterious mutations due to the population fitness decreasing because of fixation. Effective population size refers to a population that is reproducing. An increase in this population size has been correlated with a decreased rate of genetic diversity. The position of a population relative to the critical effect population size is essential to determine the effect deleterious alleles will have on fitness. If the population is below the critical effective size fitness will decrease drastically, however if the population is above the critical effect size, fitness can increase regardless of deleterious mutations due to compensatory alleles.
Sources: en.wikipedia.org
Andress, Jason. Winterfeld, Steve. (2011). Cyber Warfare: Techniques, Tactics and Tools for Security Practitioners. Syngress. ISBN 1-59749-637-5 Bodmer, Kilger, Carpenter, & Jones (2012). Reverse Deception: Organized Cyber Threat Counter-Exploitation. New York: McGraw-Hill Osborne Media. ISBN 0-07-177249-9, "ISBN 978-0-07-177249-5" Brenner, S. (2009). Cyber Threats: The Emerging Fault Lines of the Nation State. Oxford University Press. ISBN 0-19-538501-2 Carr, Jeffrey. (2010). Inside Cyber Warfare: Mapping the Cyber Underworld. O'Reilly. ISBN 978-0-596-80215-8 Conti, Gregory. Raymond, David. (2017). On Cyber: Towards an Operational Art for Cyber Conflict. Kopidion Press. ISBN 978-0-692-91156-3 Cordesman, Anthony H.; Cordesman, Justin G. (2002). Cyber-threats, Information Warfare, and Critical Infrastructure Protection: Defending the U.S. Homeland. Greenwood Publishing Group. ISBN 978-0-275-97423-7. Costigan, Sean S.; Perry, Jake (2012). Cyberspaces and global affairs. Farnham, Surrey: Ashgate. ISBN 978-1-4094-2754-4. Fritsch, Lothar & Fischer-Hübner, Simone (2019). Implications of Privacy & Security Research for the Upcoming Battlefield of Things. Journal of Information Warfare, 17(4), 72–87. Gaycken, Sandro. (2012). Cyberwar – Das Wettrüsten hat längst begonnen. Goldmann/Randomhouse. ISBN 978-3-442-15710-5 Geers, Kenneth. (2011). Strategic Cyber Security. NATO Cyber Centre.
==== MeSH D12.125.142 – amino acids, essential ==== MeSH D12.125.142.087 – arginine MeSH D12.125.142.087.500 – omega-n-methylarginine MeSH D12.125.142.308 – histidine MeSH D12.125.142.383 – isoleucine MeSH D12.125.142.441 – leucine MeSH D12.125.142.497 – lysine MeSH D12.125.142.557 – methionine MeSH D12.125.142.666 – phenylalanine MeSH D12.125.142.815 – threonine MeSH D12.125.142.875 – tryptophan MeSH D12.125.142.930 – valine
== Epidemiology == The prevalence of primary polycythemia (polycythemia vera) was estimated to be approximately 44–57 per 100,000 individuals in the United States. Secondary polycythemia is considered to be more common, but its exact prevalence is unknown. In one study using the NHANES dataset, the prevalence of unexplained erythrocytosis is 35.1 per 100,000, and was higher among males and among individuals between ages 50–59 and 60–69.
=== 2007–2013 === Helton's power and RBI production stayed relatively level to his previous year's stats during the 2007 season, as he managed 17 home runs and 91 RBI. These numbers were well below his career norms, yet Helton kept up his string of seven consecutive seasons with an on-base percentage higher than .400, nine consecutive seasons with a batting average above .300, and also walked more times than he struck out (a feat he accomplished in seven of his first ten full seasons). Helton recorded his 1,000th career hit at Coors Field on June 20, in a 6–1 home win over the New York Yankees, becoming only the fifth active player to have 1,000 career hits in one ballpark. On September 9, in 4–2 home victory over the San Diego Padres, Helton hit his 35th double of the season. This made him the only player in MLB history to have hit 35 or more doubles in at least 10 consecutive seasons (1998–2007). Helton hit his 300th career home run on September 16 in a 13–0 home win over the Florida Marlins. He became the first player to hit 300 home runs for the Rockies. The 2007 season was a wild see-saw affair for the Rockies. After they began the season with a 13-1 record, threatening to run away with the division, they underwent multiple red hot and ice cold streaks, leaving them in a desperate spot in September, as they tried to earn a playoff spot for the first time since their brief October appearance of 1995.
The argument that Belgians would believe it was butter if it was not cube shaped was disproportionate: it would "considerably exceed the requirements of the object in view" and labelling would protect consumers "just as effectively". In a 2003 case, Commission v Italy Italian law required that cocoa products that included other vegetable fats could not be labelled as "chocolate". It had to be "chocolate substitute". All Italian chocolate was made from cocoa butter alone, but British, Danish and Irish manufacturers used other vegetable fats. They claimed the law infringed article 34. The Court of Justice held that a low content of vegetable fat did not justify a "chocolate substitute" label. This was derogatory in the consumers' eyes. A 'neutral and objective statement' was enough to protect consumers. If member states place considerable obstacles on the use of a product, this can also infringe article 34. So, in a 2009 case, Commission v Italy, the Court of Justice held that an Italian law prohibiting motorcycles or mopeds pulling trailers infringed article 34. Again, the law applied neutrally to everyone, but disproportionately affected importers, because Italian companies did not make trailers. This was not a product requirement, but the Court reasoned that the prohibition would deter people from buying it: it would have "a considerable influence on the behaviour of consumers" that "affects the access of that product to the market". It would require justification under article 36, or as a mandatory requirement.
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.
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.