melanocortin receptor 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 2026-05-17. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H68N14O10 | Free base; the drug product is formulated as an acetate salt |
| Molar mass | About 1025 g/mol | Calculated for the free base |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| CAS Registry Number | 189691-06-3 | Common listing for the free base |
| Typical storage | -20 °C, desiccated, protected from light | Repeated freeze-thaw cycles are best avoided |
Bremelanotide is a cyclic heptapeptide that acts as an agonist at melanocortin receptors. It binds MC1R, MC3R, MC4R, and MC5R, with MC4R activation considered most relevant to sexual desire pathways in the central nervous system. The molecule is a synthetic analog of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation and energy regulation. Early research explored its use in tanning before attention shifted toward sexual dysfunction applications. Receptor binding affinity varies across these subtypes.
Activation of MC4R in the hypothalamus is thought to influence dopaminergic signaling, which in turn affects arousal and desire. This mechanism differs from that of phosphodiesterase type 5 inhibitors, which act primarily on vascular smooth muscle in the genital region. Because the pathway is central rather than peripheral, effects are not strictly dependent on local blood flow. The precise downstream cascade linking receptor binding to behavioral outcomes remains an area of ongoing investigation.
Clinical development of bremelanotide proceeded through several reformulation attempts. An early intranasal version was discontinued, and a subcutaneous auto-injector formulation later received approval for hypoactive sexual desire disorder in premenopausal women. Approval decisions have varied by country and over time, and the product has not been universally adopted. Blood pressure elevation is a documented effect, which is why some jurisdictions require monitoring after administration. The clinical evidence base continues to evolve as additional studies are published.
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.
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.
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.
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.
In any case, general side effects of bicalutamide that might occur in either sex include diarrhea, constipation, abdominal pain, nausea, dry skin, itching, and rash. The drug is well-tolerated at higher dosages than 50 mg/day, up to 600 mg/day, with rare additional side effects. Bicalutamide has been associated with abnormal liver function tests such as elevated liver enzymes. In the Early Prostate Cancer (EPC) clinical programme of bicalutamide for LPC and LAPC, the rate of abnormal liver function tests with bicalutamide monotherapy was 3.4% relative to 1.9% for placebo. However, higher rates, up to 11%, have been seen in other studies. Hepatic changes that have necessitated discontinuation of bicalutamide, such as marked increases in liver enzymes or hepatitis, have occurred in 0.3–1.5% of men in clinical trials, or approximately 1% overall. Elevated liver enzymes with bicalutamide usually occur within the first 3 to 6 months of treatment. Monitoring of liver function during treatment is recommended, particularly in the first few months. In men with early prostate cancer, bicalutamide monotherapy has been found to increase non-prostate cancer mortality. The reasons for the increase in mortality with bicalutamide in these men are unknown, but possible factors could include androgen deprivation or drug-related toxicity of bicalutamide. There are 10 published case reports of liver toxicity associated with bicalutamide as of 2022. Death occurred in 2 of these cases.
A codon table can be used to translate a genetic code into a sequence of amino acids. The standard genetic code is traditionally represented as an RNA codon table, because when proteins are made in a cell by ribosomes, it is messenger RNA (mRNA) that directs protein synthesis. The mRNA sequence is determined by the sequence of genomic DNA. In this context, the standard genetic code is referred to as 'translation table 1' among other tables. It can also be represented in a DNA codon table. The DNA codons in such tables occur on the sense DNA strand and are arranged in a 5′-to-3′ direction. Different tables with alternate codons are used depending on the source of the genetic code, such as from a cell nucleus, mitochondrion, plastid, or hydrogenosome. There are 64 different codons in the genetic code and the below tables; most specify an amino acid. Three sequences, UAG, UGA, and UAA, known as stop codons, do not code for an amino acid but instead signal the release of the nascent polypeptide from the ribosome. In the standard code, the sequence AUG—read as methionine—can serve as a start codon and, along with sequences such as an initiation factor, initiates translation. In rare instances, start codons in the standard code may also include GUG or UUG; these codons normally represent valine and leucine, respectively, but as start codons they are translated as methionine or formylmethionine.
Argentina was the only South American country to participate in the 1991 Gulf War. It sent a destroyer, ARA Almirante Brown (D-10), a corvette, ARA Spiro (P-43) (later replaced by another corvette, ARA Rosales (P-42)) and a supply ship, ARA Bahía San Blas (B-4) to participate on the United Nations blockade and sea control effort of the Persian Gulf. The success of "Operación Alfil" (English: "Operation Bishop") with more than 700 interceptions and 25,000 nautical miles (46,000 km) sailed in the theatre of operations helped to overcome the so-called "Malvinas syndrome". Argentina was later classified by the US as a major non-NATO ally due to its contributions during the war.
== The company == GenSpera president and CEO Craig Dionne, PhD, co-founded GenSpera in 2003. He was previously vice president of biological research at Cephalon Inc., where he was responsible for neurobiology and oncology drug discovery. GenSpera was financed by a series of private placements beginning in 2007 and became publicly traded in late 2009.
Sources: en.wikipedia.org
syphilis caused by Treponema pallidum, yaws caused by Treponema pertenue, listeriosis due to Listeria monocytogenes, Vincent's infection caused by Fusobacterium fusiforme, actinomycosis caused by Actinomyces israelii, infections caused by Clostridium species.
The thyroid gland is found in all vertebrates. In fish, it is usually located below the gills and is not always divided into distinct lobes. However, in some teleosts, patches of thyroid tissue are found elsewhere in the body, associated with the kidneys, spleen, heart, or eyes. In tetrapods, the thyroid is always found somewhere in the neck region. In most tetrapod species, there are two paired thyroid glands – that is, the right and left lobes are not joined. However, there is only ever a single thyroid gland in most mammals, and the shape found in humans is common to many other species. In larval lampreys, the thyroid originates as an exocrine gland, secreting its hormones into the gut, and associated with the larva's filter-feeding apparatus. In the adult lamprey, the gland separates from the gut, and becomes endocrine, but this path of development may reflect the evolutionary origin of the thyroid. For instance, the closest living relatives of vertebrates, the tunicates and amphioxi (lancelets), have a structure very similar to that of larval lampreys (the endostyle), and this also secretes iodine-containing compounds, though not thyroxine. Thyroxine is critical to metabolic regulation, and growth throughout the vertebrate clade. Iodine and T4 trigger the change from a plant-eating water-dwelling tadpole into a meat-eating land-dwelling frog, with better neurological, visuospatial, smell and cognitive abilities for hunting, as seen in other predatory animals.
=== Critical response === Jordan Mintzer of The Hollywood Reporter wrote that "Demoustier's depiction of the long — it took seven years from start to finish — and sordid affair behind The Great Arch's construction is a tale of lost illusions, with von Spreckelsen as a misguided genius who won the architectural lottery and wound up paying a hefty price for it. There are some clever bits of humor throughout the movie, especially involving all the shenanigans of the French, but the Dane's story ends on a decidedly dark note." For Cineuropa, Fabien Lemercier wrote that "Skilfully navigating the paradoxical dimension of his subject, tracing the path of an individual with a very human radicalism (particularly attached to hand-drawing) in the midst of a number of fairly specific professional twists and turns (regularity of joints, fixing points, foundations, support, glued glass, nitrate staining of Carrara marble, experiments, search for solutions, etc.), Stéphane Demoustier succeeds in expressing the most sensitive nuances for an uninformed audience using a patina of comedy that does not spare the French presidential royalty and its procession of senior civil servants. It's a "marriage of the dull and the shiny" that gives the film its seductive balance, its zest and its charm."
Sources: en.wikipedia.org
PT-141 is a research code for bremelanotide, a cyclic peptide that activates melanocortin receptors. It was developed for sexual dysfunction and later approved under a brand name as a subcutaneous injection. The same code is widely used by suppliers selling non-pharmaceutical material.
Both are synthetic melanocortin agonists and share a similar peptide backbone, but they are distinct molecules with different receptor profiles. Melanotan II was never approved as a medicine, whereas bremelanotide was. Findings about one compound should not be transferred to the other without direct evidence.
It is typically distributed as a lyophilized powder in sealed vials, sometimes with a separate solvent. Purity statements usually originate from the supplier rather than an independent laboratory. Storage recommendations vary between vendors, which makes comparison across sources difficult.
Bremelanotide binds several melanocortin receptors, and MC4R is the subtype most often cited as responsible for its behavioural effects. Activity at MC1R, MC3R and MC5R is also reported. Selectivity is therefore described as limited rather than precise.