If you have been reading about FSFI desire score 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 2025-10-14. 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.
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.
From a pharmacokinetic standpoint, the peptide is usually delivered by injection because oral bioavailability is very low; proteases in the digestive tract degrade it rapidly. After subcutaneous administration, plasma concentrations reach a peak within roughly one hour. Its elimination half-life is relatively short, with most reports placing it in the range of a few hours. Nasal formulations have also been examined, though absorption varies widely between individuals. Metabolism proceeds mainly through peptidase cleavage, and the resulting products are excreted by the kidneys.
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.
| 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 |
Clinical research typically uses randomised, double-blind, placebo-controlled designs. The most common primary endpoint is the desire domain score of the Female Sexual Function Index, sometimes paired with a distress measure. Secondary outcomes include arousal, satisfaction, and event-based counts of satisfying sexual episodes. Across trials, average improvements are modest and individual responses vary widely. Whether benefits persist beyond a few months, and whether they depend on baseline hormone status, remain open questions rather than settled findings.
Melanocortin receptors form a family of five G-protein-coupled receptors designated MC1 through MC5. Bremelanotide binds most strongly at MC4R and MC1R, with weaker activity reported at MC3R and MC5R. MC4R is expressed in hypothalamic nuclei that coordinate energy balance and aspects of sexual behaviour. The prevailing interpretation is that central MC4R activation, rather than peripheral vascular effects alone, drives the reported changes in desire. This account remains partly inferential, since direct receptor-level measurement in living humans is not practical.
After subcutaneous administration, plasma concentrations rise within roughly thirty minutes and the elimination half-life is short, on the order of two to three hours. Reported physiological responses include transient increases in blood pressure and nausea, which tended to diminish with repeated dosing in trial settings. Because the peptide clears quickly, effects are not expected to persist long after a dose. Absorption from non-injected routes is poorly characterised, and nasal delivery produced variable plasma levels in older work.
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 is a synthetic cyclic heptapeptide that acts on a family of G-protein-coupled receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide associated with pigmentation and several central signalling pathways. A lactam bridge constrains the ring and slows enzymatic breakdown, which distinguishes it from the linear parent molecule. Research interest moved over time from pigment biology toward central nervous system effects, particularly circuits connected to sexual desire. Parenteral delivery is used because oral bioavailability is poor.
Early clinical work used an intranasal formulation, and later programmes switched to subcutaneous delivery for more consistent absorption. A subcutaneous product received regulatory approval in the United States in 2019 for premenopausal women with acquired, generalised hypoactive sexual desire disorder. Approval followed phase 3 trials in which active treatment separated from placebo on desire and distress measures, though the average difference was modest. Labeling carries a caution about transient blood pressure elevation, so cardiovascular history is assessed before prescribing. Questions about durability of benefit beyond several months remain open.
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.
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.
== Research == In addition to major depressive disorder, aticaprant was under development for the treatment of alcoholism, cocaine use disorder, and smoking withdrawal. However, development for these indications was discontinued.
=== Hormonal evaluation === Similar to humans, a diagnosis of hypersomatotropism in cats and dogs requires demonstration of growth hormone excess or heightened IGF-1 concentrations. Growth hormone levels can be measured with a radioimmunoassay. However the cost may impact availability of this. All cats with hypersomatotropism that have been tested in studies displayed increased growth hormone levels. Some cats had significantly increased levels; in other cats, the increase was only slightly above normal levels. Cats in those studies were likely in the later stages of the disease. A single instance of elevated growth hormone levels is not indicative of hypersomatotropism, it can be the result of a secretory pulse and mildly increased growth hormone levels have been observed in diabetic cats without hypersomatotropism. The recommended practice is for several tests with 10 minute intervals. IGF-1 levels can be detected with a blood test. The vast majority of cats with hypersomatotropism have increased IGF-1 levels, most dogs with hypersomatotropism have increased IGF-1 levels. Normal levels of IGF-1 have been seen in a few cats, potentially due to these cats being at the early stages of the disease. Other causes need to be investigated in cats with normal IGF-1 levels and suspected hypersomatotropism. IGF-1 levels may be lower due to lymphoma or other diseases. IGF-1 levels can be normal in cats with hypersomatotropism when the measurement is taken prior to insulin therapy.
=== Established lesion === The hallmark of the established lesion is the overwhelming presence of plasma cells in relation to the prior stages of inflammation. Beginning two to three weeks after first plaque formation, the established lesion is widespread in both human and animals populations and can be seen commonly associated with the placement of orthodontic bands on molars. Similar to the initial and early lesions, the established lesion features an inflammatory reaction confined to the area near the base of the gingival sulcus, but unlike prior stages, displays plasma cells clustered around blood vessels and between collagen fibers outside the immediate area of the reaction site. While most of the plasma cells produce IgG, a significant number do produce IgA (and rarely, some produce IgM). The presence of complement and antigen-antibody complexes is evident throughout the connective and epithelial tissue. It is in the established lesion that epithelial proliferation and apical migration begin. In health, the junctional epithelium creates the most coronal attachment of the gum tissue to the tooth at or near the cementoenamel junction. In the established lesion of periodontal disease, the connective tissue lying subjacent to the junctional epithelium is nearly destroyed, failing to properly support the epithelium and buttress it against the tooth surface.
== Personal life == Samberg is married to musician Joanna Newsom. He described himself as her "superfan", and they met at one of her concerts in 2006. After five years of dating, Samberg proposed to her in February 2013, and they married on September 21, 2013, in Big Sur, California, with Saturday Night Live co-star Seth Meyers serving as Samberg's groomsman. In March 2014, Samberg and Newsom purchased the Moorcrest estate in the Beachwood Canyon area of Los Angeles, California, which was associated with various historical figures: in the 1920s, it was owned by the parents of actress Mary Astor; prior to that, Charlie Chaplin rented it. The couple also owns a home in Manhattan's West Village. They announced the birth of their daughter on August 8, 2017. The birth of their second child, a son, was announced by the Lonely Island's Jorma Taccone in February 2023. Samberg, who grew up in the East Bay, is a fan of the Oakland Athletics and the Golden State Warriors. Samberg was raised in a Jewish family, but considers himself "not particularly religious".
Sources: en.wikipedia.org
== External links == "Galanin Receptors". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2016-03-03. Retrieved 2007-04-24. Galanin+Receptors at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
=== Sulfhydryl-containing agents === Alacepril Captopril (trade name Capoten), the first ACE inhibitor. Zofenopril These agents appear to show antioxidative properties but may be involved in adverse events such as skin eruptions.
== Further reading == Quesada, Ivan; Tudurí, Eva; Ripoll, Cristina; Nadal, Ángel (2008-10-01). "Physiology of the pancreatic α-cell and glucagon secretion: role in glucose homeostasis and diabetes". Journal of Endocrinology. 199 (1): 5–19. doi:10.1677/JOE-08-0290. ISSN 0022-0795. PMID 18669612.
Following defeat by Napoleon in 1805, Austria was forced to cede Tyrol to the Kingdom of Bavaria in the Peace of Pressburg. Tyrol as a part of Bavaria became a member of the Confederation of the Rhine in 1806. The 1808 Bavarian constitution abolished traditional administrative divisions and replaced them with Kreise; Tyrol's territory was split up into:
== GSNOR == The enzyme GSNO reductase (GSNOR) reduces S-nitrosoglutathione (GSNO) to an unstable intermediate, S-hydroxylaminoglutathione, which then rearranges to form glutathione sulfonamide, or in the presence of GSH, forms glutathione disulfide and hydroxylamine.
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.
It primarily activates specific subtypes in the melanocortin receptor family. These receptors are G protein-coupled and mediate signaling mainly within the central nervous system.