If you have been reading about PT-141 code and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-02-05. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solubility class | Freely soluble in water | Also soluble in DMSO and some alcohols |
| Typical storage temperature | -20 C or below | Desiccated, protected from light |
| Common analytical method | RP-HPLC with UV detection | Often paired with mass spectrometry |
| Typical reported purity | 95 percent or higher | Reference-grade material |
| Common synonyms | PT-141 | Also called bremelanotide acetate |
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.
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.
In medicine, oxygen saturation, commonly referred to as "sats", measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. At low partial pressures of oxygen, most hemoglobin is deoxygenated. At around 90% (the value varies according to the clinical context) oxygen saturation increases according to an oxygen-hemoglobin dissociation curve and approaches 100% at partial oxygen pressures of >11 kPa. A pulse oximeter relies on the light absorption characteristics of saturated hemoglobin to give an indication of oxygen saturation.
== Society and culture == Ethylmorphine was first marketed in France in 1953 by Houde, and in Norway and Spain in 1960. It is not marketed in the United States and is a Schedule II controlled substance.
During 2020, as the COVID‑19 pandemic escalated globally and vaccine development intensified, the World Health Organization (WHO) COVAX facility adopted the motto "No one is safe unless everyone is safe" to emphasize the need for equitable vaccination. The facility set a goal of supplying COVID‑19 vaccines to nearly 100 low-to-middle income countries that could not afford them. COVAX sought to fundraise US$6.8 billion to purchase and deliver vaccines to participating countries in proportion to their populations. On 18 December 2020, the facility announced agreements with vaccine manufacturers to supply 1.3 billion doses for 92 low-middle income countries in the first half of 2021. Yet, by mid-December, some 16 countries representing only 14% of the world's population had preordered more than 10 billion vaccine doses or about 51% of the available world supply. Specifically, Canada, Australia, and Japan – having only 1% of the world's COVID‑19 cases – had collectively reserved some 1 billion vaccine doses, while the COVAX facility had reserved only a few hundred million doses. At the Group of Seven summit in June 2021, the United States promised to distribute 500 million vaccine doses internationally; this distribution began on 17 August. Preorders from rich countries were made during 2020 with 13 different vaccine manufacturers, whereas those for low-to-middle income countries were made primarily for the Oxford–AstraZeneca COVID-19 vaccine, which is lowest in cost and has no special refrigeration needs.
Sources: en.wikipedia.org
== Structure == The gene coding for DPEP1 is 6 kb long and consists of ten exons and nine introns. The protein itself is made of 411 amino acid residues and is only transcribed in kidney cells. Although disulfide linkages in DPEP1 do not contribute to the enzyme’s activity, they are essential for the enzyme’s proper function because they keep the enzyme’s subunits together and attached to the renal brush border. Cysteine 261 is involved in disulfide linkage between the enzyme’s subunits, and is also located very close to both the site of the GPI-anchor and the membrane, suggesting that it is also involved in the enzyme’s linkage to the membrane. DPEP1 is also a metalloenzyme that specifically uses zinc as its cofactor. The enzyme’s typical zinc content is 1.42 ug/mg. The addition of cobalt or manganese ions cause the enzyme to take on different conformations, which suggests that the enzyme may be able to hydrolyze different dipeptides depending on which metal ions are present—aka the metal-content of one’s micronutrient intake could affect their renal dipeptidase’s ability to metabolize various dipeptides.
=== Flow probes for NMR spectroscopy === Real-time applications of NMR in liquid media have been developed using specifically designed flow probes (flow cell assemblies) which can replace standard tube probes. This has enabled techniques that can incorporate the use of high performance liquid chromatography (HPLC) or other continuous flow sample introduction devices. These flow probes have used in various online process monitoring such as chemical reactions, environmental pollutant degradation.
== Use == Like other alkylalkanolamines, N-methylethanolamine is used in water- and solvent-based paints and coatings as a solubilizer for other components, such as pigments and as a stabilizer. In cathodic dip-coating, N-methylaminoethanol serves as cation neutralizer for the partial neutralization of the epoxy resin. It also serves as a chain extender in the reaction of high molecular weight polyepoxides with polyols. Being a base, N-methylaminoethanol forms neutral salts with fatty acids, which are used as surfactants (soaps) with good emulsifying properties and find applications in textile and personal care cleansing products. When bleaching cotton-polyester blends, NMEA is used as a brightener. By methylation of N-methylaminoethanol, dimethylaminoethanol and choline [(2-hydroxyethyl)-trimethyl-ammonium chloride] can be prepared. In the reaction of N-methylaminoethanol with fatty acids, long-chain N-methyl-N-(2-hydroxyethyl)amides are formed upon elimination of water. These are used as neutral surfactants. Such amides also act as flow improvers and pour point depressants in heavy oils and middle distillates. By catalytic oxidation of N-methylaminoethanol, the non-proteinogenic amino acid sarcosine is obtained. N-methylaminoethanol plays a role as a building block for the synthesis of crop protection compounds and pharmaceuticals, such as in the first stage of the reaction sequence to the antihistamine and antidepressant mianserin (Tolvin) and to the non-analgesic Nefopam (Ajan).
The Irish Free State (6 December 1922 – 29 December 1937), also known by its Irish name Saorstát Éireann, was the Irish state established in December 1922 under the Anglo-Irish Treaty of December 1921, initially as a Dominion. The treaty ended the three-year Irish War of Independence between the forces of the Irish Republic—the Irish Republican Army (IRA)—and British Crown forces. As per the 6 December 1922 Constitution of the Irish Free State, the new state was called the Irish Free State and became a Dominion of the British Empire. It comprised 26 of the 32 counties of Ireland. Northern Ireland, which was made up of the remaining six counties, exercised its right under the Treaty to opt out of the new state. The Free State government consisted of the governor-general—the representative of the king—and the Executive Council (cabinet), which replaced both the revolutionary Dáil Government and the Provisional Government set up under the Treaty. W. T. Cosgrave, who had led both of these administrations since August 1922, became the first president of the Executive Council (prime minister). The Oireachtas or legislature consisted of Dáil Éireann (the lower house) and Seanad Éireann (the upper house), also known as the Senate. Members of the Dáil were required to take an Oath of Allegiance to the Constitution of the Free State and to declare fidelity to the king. The oath was a key issue for opponents of the Treaty, who refused to take it and therefore did not take their seats.
Sources: en.wikipedia.org
The peptide is polar and charged, and reversed-phase chromatography with acidic mobile phases resolves it well from related substances. Ultraviolet detection near 214 nm gives adequate sensitivity without derivatisation.
Aqueous solutions are subject to oxidation and hydrolysis, so concentration and pH drift can occur even under refrigeration. Solid, dry material held cold and desiccated degrades far more slowly.
Mass spectrometry separates the parent from analogues that differ by a single modification, such as an amide versus acid terminus. Retention time alone is less reliable because closely related peptides can co-elute.
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.