The short version of melanocortin receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-06-18. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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 |
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.
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.
PT-141 initiates cellular signaling by binding to specific subtypes within the melanocortin receptor family. These receptors belong to the G protein-coupled receptor superfamily, and activation raises intracellular cyclic adenosine monophosphate levels. This cascade ultimately influences neuronal circuits in the central nervous system that are associated with sexual desire and arousal. Research indicates the compound's action concentrates in hypothalamic regions rather than peripheral tissues, which helps explain some observed pharmacological features. The selectivity of receptor binding underlies its functional differences.
Compared with the related compound melanotan II, PT-141 shows markedly weaker activation of receptors tied to pigmentation. This difference stems from subtle structural variations that alter affinity distribution across receptor subtypes. Investigators propose that such selectivity produces a different side effect profile in specific applications. However, downstream consequences of prolonged receptor activation remain uncertain in the literature. Published studies do not fully agree on the duration of signaling pathway activity and the mechanisms of desensitization.
== Other activities == Robert Finnigan served on the board of directors of the trade organization American Electronics Association (AEA). He and Dean O. Morton were founders of the AEA's Environmental and Occupational Health activities. Finnigan also co-founded the Organization Internationale Metrology Legale (OIML) for legal metrology. With the support of the National Bureau of Standards (NBS) they developed protocols for international regulations in fifty-one nations. In many cases, these closely matched the standards of the EPA.
By combining these two aspects (need for connectivity and land take imposed by cemeteries), two positive results can be achieved: protecting memories of the past and connecting ecosystems with multiple-use corridors. Green burials appeal to people for economic reasons. Traditional burial practices can be a financial burden causing some to turn to green burials as a cheaper alternative. Some people view green burials as more meaningful, especially for those who have a connection to a piece of land, such as current residence or other places that hold meaning for them.
=== Extraction methods === Prior to analysis, YTXs must be isolated from the sample medium whether this is the digestive gland of a shellfish, a water sample, or a growth-culture medium. This can be achieved by several methods:
== Awards and honours == Robinson has received many honors working as a cellular biologist. She was awarded a Wellcome Trust Principal Research Fellowship in 1999 and in 2003 she was appointed Professor of Molecular Cell Biology. She was elected a Fellow of the Academy of Medical Sciences in 2001 and member of the European Molecular Biology Organization in the same year. She was elected a Fellow of the Royal Society (FRS) in 2012. The Wellcome Trust also has funded her research for over 25 years.
Lee recalled that it was Danniels who deemed him "not suitable, for whatever reasons he had", but Lifeson noted that Rutsey, whose influential personality often steered the group, had pushed for a different bassist and went along with the decision. Following Lee's exit, Rutsey recruited bassist Joe Perna and renamed the band to Hadrian. However, after a poorly received performance with Perna, Rutsey and Lifeson invited Lee to rejoin in September 1969. Lee said: "I got a call from John and he said, 'Can we get together?' Basically, 'Can you come back? We're sorry.'" Young left the group to study at college; following brief tenures by second guitarist Bob Vopni in 1969 and rhythm guitarist Mitch Bossi in 1971, the lineup stabilised as a power trio of Lifeson, Rutsey and Lee by 1972. The group refined their live performances through extensive touring of the Ontario high school circuit. Drawing heavy influence from Led Zeppelin's debut album, Rush developed a blues-based hard rock sound characterised by Lee's increasingly high-register falsetto. During this period, Danniels struggled to secure consistent bookings as the band began prioritising original material over standard covers in their live sets. The band's professional trajectory shifted in 1971 following a legislative change that lowered Ontario’s legal drinking age from 21 to 18. This allowed the group to play bars and clubs, a move Lee described as the catalyst for their evolution from a "casual garage act" into a professional unit performing six nights a week.
Sources: en.wikipedia.org
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=== Other compounds === Tetraselenium tetranitride, Se4N4, is an explosive orange compound analogous to tetrasulfur tetranitride (S4N4). It can be synthesized by the reaction of selenium tetrachloride (SeCl4) with ([(CH3)3Si]2N)2Se. Selenium reacts with cyanides to yield selenocyanates:
== Computing initiatives == Novel initiatives include partnering between governmental organizations and industry, such as the European Innovative Medicines Initiative. The US Food and Drug Administration created the "Critical Path Initiative" to enhance innovation of drug development, and the Breakthrough Therapy designation to expedite development and regulatory review of candidate drugs for which preliminary clinical evidence shows the drug candidate may substantially improve therapy for a serious disorder. In March 2020, the United States Department of Energy, National Science Foundation, NASA, industry, and nine universities pooled resources to access supercomputers from IBM, combined with cloud computing resources from Hewlett Packard Enterprise, Amazon, Microsoft, and Google, for drug discovery. The COVID-19 High Performance Computing Consortium also aims to forecast disease spread, model possible vaccines, and screen thousands of chemical compounds to design a COVID-19 vaccine or therapy. In May 2020, the OpenPandemics – COVID-19 partnership between Scripps Research and IBM's World Community Grid was launched. The partnership is a distributed computing project that "will automatically run a simulated experiment in the background [of connected home PCs] which will help predict the effectiveness of a particular chemical compound as a possible treatment for COVID-19".
=== Vacuum system === The specimen should be in a high-vacuum environment for optimal milling results. The vacuum makes sure that there are few air particles that could interfere with the ion beam. This way, all the energy in the energy beam can be transferred to the surface with much less energy loss.
== Toxicity == An in silico Study analyzing potential risks of 3-HO-PCE, along with other related substances, found multiple potential risks. One such risk was a high probability of hERG blockades, suggesting that QT-prolongation could be present in use. The lungs, liver, and blood were all found to be prominent likely toxicity targets of this class of drugs. The LD50 of 3-HO-PCE and related substances in rats was consistently between 200-630mg/kg orally, indicating moderate oral toxicity.
Sources: en.wikipedia.org
Acantharea, a relatively large group of marine radiolarian protozoa, produce intricate mineral skeletons composed of strontium sulfate. In biological systems, calcium is substituted to a small extent by strontium. In the human body, most of the absorbed strontium is deposited in the bones. The ratio of strontium to calcium in human bones is between 1:1000 and 1:2000, roughly in the same range as in the blood serum.
== Diagnosis == One of the most important factors used to determine the clinical suspicion of malignancy of an adnexal mass is the sonographic (ultrasound) appearance of the mass. Indications that the mass is at a higher risk of being malignant include the presence of loculations, nodules, papillary structures, septations, or a size greater than 10 cm.
== Receptors == In zebrafish, the trace amine-associated receptor 13c (or TAAR13c) has been identified as a high-affinity receptor for cadaverine. In humans, molecular modelling and docking experiments have shown that cadaverine fits into the binding pocket of the human TAAR6 and TAAR8.
In order to strengthen security and stability in Iraq, and thereby contribute to international peace and stability, and to enhance the ability of the Republic of Iraq to deter all threats against its sovereignty, security, and territorial integrity, the Parties shall continue to foster close cooperation concerning defense and security arrangements without prejudice to Iraqi sovereignty over its land, sea, and air territory.
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.
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.