bremelanotide 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.
Last reviewed on 2026-05-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid before reconstitution |
| Solubility class | Soluble in water and aqueous buffers | Stock solutions often prepared in sterile water |
| Typical storage temperature | Minus twenty degrees Celsius or below | Dry powder, protected from light |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Ultraviolet detection near 214 nanometres |
| Common synonyms | PT-141 and bremelanotide | Code and generic name used interchangeably |
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.
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.
Published studies differ in design, population and endpoint definition, so results are not always directly comparable across reports. Some trials used patient-reported measures of desire and distress, while others tracked physiological or behavioural outcomes. Questions that remain open include the durability of effects beyond short follow-up periods, the frequency of transient blood pressure elevation observed after administration, and whether a subtype-selective analogue could separate central effects from pigmentation-related activity. These points are usually framed as unresolved rather than settled in review literature.
Routine characterisation of bremelanotide relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nm, where the peptide backbone absorbs. Mass spectrometry, typically in tandem mode with electrospray ionisation, confirms identity and supports quantification in biological matrices. Additional checks include amino acid analysis, peptide mapping after enzymatic digestion, and confirmation of the lactam bridge, since incomplete cyclisation produces a mass-shifted by-product. Purity values above 95 percent are common in reference-grade material, though reports vary in how strictly related substances are resolved from the parent peak.
The lyophilised solid is relatively stable when kept dry, protected from light and held at reduced temperature, commonly minus 20 degrees Celsius or lower for long-term storage. In solution the peptide is more vulnerable: tryptophan oxidation, hydrolysis of the lactam bridge and aggregation all become relevant over time, and the rate depends on pH, buffer composition and concentration. Repeated freeze-thaw cycles are generally avoided because they promote aggregation. Aqueous working solutions are typically prepared fresh or split into single-use aliquots to limit degradation before analysis.
== Structure == Cyclotides have a well-defined three-dimensional structure due to their interlocking disulfide bonds and cyclic peptide backbone. Backbone loops and selected residues are labeled on the structure to help orientation. The amino acid sequence (single-letter amino acid representation) for this peptide is indicated on the sequence diagram to the right. One of the interesting features of cyclic peptides is that knowledge of the peptide sequence does not reveal the ancestral head and tail; knowledge of the gene sequence is required for this. In the case of kalata B1 the indicated glycine (G) and asparagine (N) amino acids are the terminal residues that are linked in a peptide bond to cyclize the peptide.
Common adverse drug reactions associated with the use of buprenorphine, similar to those of other opioids, include nausea and vomiting, drowsiness, dizziness, headache, memory loss, cognitive and neural inhibition, perspiration, itchiness, dry mouth, shrinking of the pupils of the eyes (miosis), orthostatic hypotension, male ejaculatory difficulty, decreased libido, and urinary retention. Constipation and central nervous system (CNS) effects are seen less frequently than with morphine. Central sleep apnea has also been reported as a side effect of long-term buprenorphine use.
=== United States === Under the Controlled Substances Act, dihydromorphine is listed as a Schedule I substance along with heroin. In the United States, its role in the production of dihydrocodeine and other related drugs make it a Schedule I substance with one of the higher annual manufacturing quotas granted by the US Drug Enforcement Administration: 3300 kilograms in 2013. Manufacturers, distributors, and importers with the correct DEA license and state permits related thereto are able to use Schedule I drugs in this fashion when they are transformed into something of a lower schedule. The DEA has assigned dihydromorphine and all of its salts, esters, etc. the ACSCN of 9145. As with nicomorphine, MDMA and heroin, dihydromorphine is also used in research in properly licensed facilities. US DEA Form 225, the most common and least expensive individual researcher's license, does not include Schedule I drugs, and so the lab must have a higher-level DEA registration. As with other licit opioids used for medical purposes in other countries, including even much weaker opioids like nicocodeine, benzylmorphine, and tilidine, the reason for dihydromorphine being in Schedule I is that it was not in medical use in the US at time the Controlled Substances Act of 1970 was drawn up.
Sources: en.wikipedia.org
6 February – Around eight million people on means tested benefits begin to receive the final scheduled cost-of-living payment from the UK government, as Sunak tells the BBC the financial pressures on households are beginning to ease. 7 February The government announces that dentists will be offered a £20,000 bonus to work in the areas of England with the poorest access to NHS care. Data published by Halifax Bank indicates that UK house prices increased by 2.5% in January 2024 when compared to the same month in 2023. The Met Office issues two amber snow warnings for the following day covering north Wales, north-west Shropshire, the Peak District and south Pennines. 8 February The UK government confirms that more than 100 school buildings containing reinforced autoclaved aerated concrete will be rebuilt or refurbished. Sir Keir Starmer insists he has no choice but to ditch Labour's £28 billion a year green investment pledge. 9 February Weather warnings remain in place as snow and rain continue to fall across the UK. Police tell reporters they believe that Abdul Shakoor Ezedi may have drowned in the River Thames, based on CCTV of the suspect at Chelsea Bridge. The Duke of Sussex settles his remaining phone hacking claims against Mirror Group Newspapers, with the newspaper agreeing to pay his legal costs along with around £300,000 in compensation. 10 February Police begin a search of the River Thames for the body of Abdul Shakoor Ezedi, the Clapham chemical attack suspect. A light aircraft crashes into the garden of a property in Bodffordd, Anglesey.
== External links == JPL Develops High-Speed Test to Improve Pathogen Decontamination at the Wayback Machine (archived 2016-03-04) at JPL. Spotting Spores at the Wayback Machine (archived 2016-03-04) at Astrobiology Magazine.
Sovateltide (development names IRL-1620 and PMZ-1620, sold in India under the brand name Tyvalzi) is a synthetic analog of endothelin-1 that works as a selective endothelin-B receptor agonist. In May 2023, it was approved in India to treat acute ischemic stroke. The drug was developed by Pharmazz. Sovateltide stimulates neural progenitor cells in the brain and promotes neurovascular remodeling by forming new neurons (neurogenesis) and blood vessels (angiogenesis). Sovateltide also protects neural mitochondria and enhances their biogenesis.
Furthermore, Oxgr1 gene knockout mice drinking sodium bicarbonate-rich water developed metabolic alkalosis (body tissue pH levels higher than normal) that was associated with blood bicarbonate levels significantly higher and blood chloride levels significantly lower than those in control mice drinking the sodium bicarbonate-rich water. Several other studies confirmed these findings and reported that cells in the proximal tubules of mice synthesize α-ketoglutarate and either broke it down thereby reducing its urine levels or secreted it into the tubules' lumens thereby increasing its urine levels. Another study showed that a) In silico computer simulations strongly suggested that α-ketoglutarate bound to mouse OXGPR1; b) suspensions of canal duct cells isolated from the collecting ducts, loops of Henle, vasa recta, and interstitium of mouse kidneys raised their cytosolic ionic calcium, i.e., Ca2+ levels in response to α-ketoglutarate but this response (which is an indicator of cell activation) was blocked by pretreating the cells with montelukast; and c) compared to mice not treated with streptozotocin, streptozotocin-induced diabetic mice (an animal disease model of diabetes) urinated only a small amount of the ionic sodium (Na+) that they drank or received by intravenous injections; montelukast reversed this defect in the streptozotocin-pretreated mice.
Sources: en.wikipedia.org
Purity is normally expressed as a percentage of total peak area from a chromatographic run. The value depends on the column, gradient and detection wavelength chosen. Results generated under different conditions are therefore not always interchangeable.
Cycling between frozen and thawed states promotes aggregation and can reduce the amount of soluble peptide. Adsorption to container walls also removes material from solution over time. Suppliers generally recommend aliquoting before freezing to limit the number of cycles.
A typical certificate lists lot number, appearance, purity by chromatographic area, identity confirmation and the analytical methods used. Some suppliers add endotoxin or residual solvent results. The document describes the tested lot only and does not extend to other batches.
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.