This is a working overview of GLP-1 analogue, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-16 and is reviewed periodically as new material appears.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
纯度评价多采用反相高效液相色谱，流动相常加入三氟乙酸或甲酸作为离子对改性剂，检测波长设在二百一十四纳米或二百二十纳米。分子量确认依靠电喷雾电离质谱或基质辅助激光解吸电离质谱，实测值应与理论值在数 ppm 内吻合。肽图分析通过酶切后液相色谱串联质谱完成，用于核查序列与修饰位点。体积排阻色谱用于定量共价与非共价聚集体。生物基质浓度测定则采用免疫分析或液相色谱串联质谱。
肽类的主要降解路径包括天冬酰胺脱酰胺、甲硫氨酸氧化、天冬氨酸异构化以及由 β-折叠驱动的聚集，这些反应对 pH 与缓冲液种类较为敏感。磷酸盐、丙二醇与苯酚等辅料会影响局部微环境与界面行为。强制降解研究借助高温、强光、氧化剂与极端 pH 暴露来预测产物谱。关于长期室温存放的数据相对有限，超出标签条件的稳定性仍属开放问题，需要在具体制剂中通过实时与加速试验加以确认。
容器与密封系统同样参与稳定性表现。硅油涂层、胶塞材质与顶空氧含量可能改变聚集速率与氧化水平。分析结果因此需要在完整包装形式下评估，而不能仅凭原料药数据推断。法规文件通常要求同时提交批次数据与代表性容器中的稳定性趋势。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
Storage guidance for the finished injectable product distinguishes the unused state from the in-use state. Before first use, pens are kept refrigerated between 2 and 8 degrees Celsius, protected from light, and never frozen, since freezing can disrupt the peptide or the device. After first use, label instructions in several markets permit storage at room temperature up to about 30 degrees Celsius for a limited number of days. Solid research-grade material is normally held at or below minus 20 degrees Celsius, often with desiccant, and allowed to equilibrate before opening.
Quantification and purity assessment rely on separation methods coupled to optical or mass detection. Reversed-phase high-performance liquid chromatography resolves the intact peptide from related impurities and is the standard assay technique. Size-exclusion chromatography measures aggregates, while ion-exchange chromatography separates charge variants produced by deamidation. Mass spectrometry confirms identity and detects mass shifts of a few daltons. In biological matrices, liquid chromatography with tandem mass spectrometry is often used because immunoassays can cross-react with endogenous GLP-1 or with circulating fragments.
As a peptide, semaglutide is sensitive to conditions that break amide bonds or modify side chains. Deamidation of asparagine and glutamine residues, oxidation of methionine and tryptophan, and non-covalent aggregation are the main degradation routes described in published stability work. Rate depends strongly on pH, buffer species, ionic strength, temperature and exposure to light. Formulators therefore choose a defined solution pH and often add excipients such as phosphate buffer, propylene glycol and phenol, each of which plays a separate role in pH control, tonicity or preservation.
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
Development began in the early 2010s with the goal of extending GLP-1 activity beyond the brief window achieved by native peptide infusion. The earliest approved formulation was a subcutaneous injection given once weekly. A later oral tablet pairs the peptide with an absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, usually shortened to SNAC. That carrier lowers local pH and helps the peptide cross gastric tissue. Both routes deliver the same active molecule.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, a gut hormone released after meals. Its backbone retains the GLP-1 sequence but incorporates two substitutions that slow enzymatic breakdown by dipeptidyl peptidase-4. A short polyethylene glycol linker and a C18 fatty diacid are attached to the peptide chain, allowing the molecule to bind serum albumin and remain in circulation far longer than the native hormone. The result is a circulating half-life measured in days rather than the minutes typical of endogenous GLP-1.
== Function == Proteins of the matrix metalloproteinase (MMP) family are involved in the breakdown of extracellular matrix proteins and during tissue remodeling in normal physiological processes, such as embryonic development and reproduction, as well as in disease processes, such as arthritis, and tumour metastasis. Most MMPs are secreted as inactive proproteins which are activated when cleaved by extracellular proteinases. The MMP-3 enzyme degrades collagen types II, III, IV, IX, and X, proteoglycans, fibronectin, laminin, and elastin. In addition, MMP-3 can also activate other MMPs such as MMP-1, MMP-7, and MMP-9, rendering MMP-3 crucial in connective tissue remodeling. The enzyme is also thought to be involved in wound repair, progression of atherosclerosis, and tumor initiation. In addition to classical roles for MMP3 in extracellular space, MMP3 can enter in cellular nuclei and control transcription.
== Clinical significance == Mutations in this gene are associated with type II Stickler syndrome and with Marshall syndrome. Stickler syndrome, type II is an autosomal dominant condition caused by a mutation in the COL11A1 gene. Features of Stickler syndrome type II include: sensorineural hearing loss, facial features (flat facial profile, anteverted nares, micrognathia), cleft palate, visual disturbances (type 2 vitreous anomaly, childhood-onset myopia, glaucoma, cataracts and retinal detachment), spondyloepiphyseal dysplasia, and arthropathy.
Costochondritis: Inflammation of cartilage in the ribs, causing chest pain. Spinal disc herniation: Asymmetrical compression of an intervertebral disc ruptures the sac-like disc, causing a herniation of its soft content. The hernia often compresses the adjacent nerves and causes back pain. Relapsing polychondritis: a destruction, probably autoimmune, of cartilage, especially of the nose and ears, causing disfiguration. Death occurs by asphyxiation as the larynx loses its rigidity and collapses. Tumors made up of cartilage tissue, either benign or malignant, can occur. They usually appear in bone, rarely in pre-existing cartilage. The benign tumors are called chondroma, the malignant ones chondrosarcoma. Tumors arising from other tissues may also produce a cartilage-like matrix, the best-known being pleomorphic adenoma of the salivary glands. The matrix of cartilage acts as a barrier, preventing the entry of lymphocytes or diffusion of immunoglobulins. This property allows for the transplantation of cartilage from one individual to another without fear of tissue rejection.
Tumor that can affect bone in several ways. Examples of benign bone tumors include osteoma, osteoid osteoma, osteochondroma, osteoblastoma, enchondroma, giant-cell tumor of bone, and aneurysmal bone cyst.
== Career == Baldwin began acting professionally as a teenager, landing the role of Ricky Linderman in the Chicago-set film My Bodyguard (1980). That same year he appeared in Robert Redford's Academy Award-winning drama Ordinary People as Kevin Stillman. In the early 1980s he continued with supporting roles in films including D.C. Cab (1983) and Reckless (1984). By the late 1980s he had moved into higher-profile studio productions, including Stanley Kubrick's Vietnam War film Full Metal Jacket (1987), in which he played the Marine nicknamed "Animal Mother," and the crime thriller Next of Kin (1989). In the 1990s he appeared in a run of mainstream features including Predator 2 (1990), the western biopic Wyatt Earp (1994) portraying Tom McLaury, and the science-fiction blockbuster Independence Day (1996). He later played Captain Wilkins in Roland Emmerich's Revolutionary War film The Patriot (2000). On television, Baldwin became a regular cast member of Joss Whedon's science-fiction series Firefly (2002–2003) as the mercenary Jayne Cobb, and reprised the role in the continuation film Serenity (2005). From 2007 to 2012 he played the National Security Agency agent John Casey on NBC's action-comedy series Chuck. His other television work includes a regular role on ABC's Day Break (2006–2007) and a lead role on the 1996–1997 drama series The Cape as Col. Jack Riles. He made a brief on-screen return to the schoolyard premise of My Bodyguard with a cameo in the comedy Drillbit Taylor (2008), noted as an explicit nod to his earlier film.
Sources: en.wikipedia.org
=== Polymeric micelles === Polymeric micelles are drug carriers formed by the aggregation of some amphiphile\amphiphilic molecule with an amphiphilic block copolymer. These carriers form at some high concentration specific to the compounds used, called the critical micelle concentration. The addition of an amphiphilic block copolymer effectively lowers this critical micelle concentration by shifting the monomer exchange equilibrium. These carriers are comparable to liposomes, however the lack of an aqueous core makes polymeric micelles less accommodating to a wide variety of drugs.
=== Miscellaneous === Mogo appears in the Injustice: Gods Among Us prequel comic. He travels to Earth with the Green Lantern Corps to combat Superman's Regime and the Sinestro Corps until Superman pushes him into Earth's sun.
The method, known as the Kolbe-Schmitt reaction, entails nucleophilic attack of the phenoxide on carbon dioxide. In some cases, alkenes undergo hydrocarboxylation using a mixture of carbon dioxide and H2:
The recent epidemic increase of obesity prevalence has thus contributed to changes in the prevalence and in the characteristics of pediatric OSA, the severity of OSA is proportional to the degree of obesity. Obesity leads to narrowing of the upper airway structure due to fatty infiltration and fat deposits in the anterior neck region and cervical structures. Alongside with the additional weight loading on the respiratory system, it increases the risk of pharyngeal collapsibility while reducing the intrathoracic volume and diaphragm excursion. Moreover, excessive daytime sleepiness resulting from sleep fragmentation can decrease physical activity and thus lead to weight gain (by sedentary habits or increased food intake to overcome somnolence). The obesity-related obstruction of upper airway structure has led some authors to distinguish between two types of OSA in children: type I is associated with marked lymphadenoid hypertrophy without obesity and type II is first associated with obesity and with milder upper airway lymphadenoid hyperplasia. The two types of OSA in children can result in different morbidities and consequences. Studies have shown that weight loss in obese adolescents can reduce sleep apnea and thus the symptoms of OSA.
== Clinical significance == An abdominal muscle strain, also called a pulled abdominal muscle, is an injury to one of the muscles of the abdominal wall. A muscle strain occurs when the muscle is stretched too far. When this occurs the muscle fibers are torn. Most commonly, a strain causes microscopic tears within the muscle, but occasionally, in severe injuries, the muscle can rupture from its attachment. A rectus sheath hematoma is an accumulation of blood in the sheath of the rectus abdominis muscle. It causes abdominal pain with or without a mass. The hematoma may be caused by either rupture of the epigastric artery or by a muscular tear. Causes of this include anticoagulation, coughing, pregnancy, abdominal surgery and trauma. With an ageing population and the widespread use of anticoagulant medications, there is evidence that this historically benign condition is becoming more common and more serious. On abdominal examination, people may have a positive Carnett's sign. Most hematomas resolve without treatment, but they may take several months to resolve.
Sources: en.wikipedia.org
Carbohydrates are usually present, often in a mix of simple sugars like glucose and more complex oligosaccharides such as maltodextrin which are supposed to provide more sustained energy. Carbohydrates cause an increase in serotonin levels. These are used both to provide a sweet taste and fuel for exercise, though evidence for whether they actually enhance exercise performance is mixed. Protein supplements, usually in a palatable powdered form such as whey protein or rice protein, are also commonly used both for flavour and as a fuel for muscle growth and recovery. Electrolytes providing sodium, potassium and magnesium (and often others such as zinc, calcium, iron etc in smaller amounts) are often included to replace those lost due to sweating during heavy exercise, generally as a mixture of different salts, sometimes including exotic forms such as zinc monomethionine aspartate or calcium fructoborate which are supposed to be better absorbed or have other special properties. Electrolytes help the body perform homeostasis and prevent dehydration. Nitrate salts are commonly included (often as "beetroot extract") for their supposed benefits for endurance exercise. Sometimes this is achieved by using nitrate salts of other ingredients (e.g. arginine nitrate, creatine nitrate). Creatine, a natural chemical created in the kidneys and liver, is used supposedly to improve physical performance. It also promotes an increase in muscle growth. β-Alanine is a common ingredient found in 87% of leading pre-workout formulas.
=== Heavy metal emissions in the air === In some circumstances, mainly depending on the origin and the composition of the raw materials used, the high-temperature calcination process of limestone and clay minerals can release in the atmosphere gases and dust rich in volatile heavy metals, e.g. thallium, cadmium and mercury are the most toxic. Heavy metals (Tl, Cd, Hg, ...) and also selenium are often found as trace elements in common metal sulfides (pyrite (FeS2), zinc blende (ZnS), galena (PbS), ...) present as secondary minerals in most of the raw materials. Environmental regulations exist in many countries to limit these emissions. As of 2011 in the United States, cement kilns are "legally allowed to pump more toxins into the air than are hazardous-waste incinerators."
== Treatment == ILD is not a single disease but encompasses many different pathological processes, hence treatment is different for each disease. If a specific occupational exposure cause is found, the person should avoid that environment. If a drug cause is suspected, that drug should be discontinued.
=== Detection in body fluids === Diphenhydramine can be quantified in blood, plasma, or serum. Gas chromatography with mass spectrometry (GC-MS) can be used with electron ionization on full scan mode as a screening test. GC-MS or GC-NDP can be used for quantification. Rapid urine drug screens using immunoassays based on the principle of competitive binding may show false-positive methadone results for people having ingested diphenhydramine. Quantification can be used to monitor therapy, confirm a diagnosis of poisoning in people who are hospitalized, provide evidence in an impaired driving arrest, or assist in a death investigation.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
冻融过程中冰晶形成与局部浓度升高会促使肽链发生界面吸附和聚集。聚集不仅降低有效含量，还会改变可见异物与不溶性微粒的计数结果。将溶液分装为单次使用的小体积等份可减少循环次数。