GLP-1 receptor agonist raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-09-19. Anything still debated is marked as such rather than presented as settled.
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物，其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代，使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸，进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链，该侧链赋予分子与血浆白蛋白结合的能力。
The distinction between established facts and open questions matters here. That the peptide binds the GLP-1 receptor and stimulates insulin release in a glucose-dependent manner is well documented. How individual variability in receptor density, gastric emptying rate, and gut microbiome composition shapes response remains an active research area. Long-term outcomes beyond five years of continuous use are not yet fully characterized in published trials, and several extension studies are ongoing.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C187H291N45O59 | 按主链与 C18 二酸侧链计算 |
| 分子量 | 约 4113.6 道尔顿 | 游离碱形式，随反离子略有差异 |
| 外观 | 白色至类白色冻干粉末 | 具吸湿性，需干燥保存 |
| 溶解性 | 微溶于水，易溶于碱性缓冲液 | 溶解性随 pH 升高而改善 |
| 等电点 | 约 5.4 | 影响缓冲液选择与聚集倾向 |
Two structural features account for the prolonged half-life of semaglutide. A modified amino acid at position 8 resists cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1. A fatty diacid side chain binds serum albumin, which limits renal clearance and protects the peptide from enzymatic breakdown. These modifications yield a plasma half-life of approximately one week in humans, allowing once-weekly administration. The relationship between plasma concentration and clinical effect varies between individuals, and sources of that variability are still being characterized.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
Reverse-phase high-performance liquid chromatography is the standard method for purity assessment, separating the peptide from truncated or oxidized variants. Mass spectrometry confirms molecular mass and detects modifications, while ultraviolet absorbance near 280 nanometers supports concentration measurement through tryptophan and tyrosine residues. Circular dichroism can indicate secondary structure, though the peptide is largely helical in solution, and ion-exchange chromatography resolves charge variants. Purity values above 95 percent are typical for research-grade material. Stability studies track degradation over time under defined conditions.
Lyophilized semaglutide is typically stored at temperatures between minus 20 and minus 80 degrees Celsius for long-term preservation. Short-term storage at 2 to 8 degrees Celsius is common for working aliquots. Repeated freeze-thaw cycles can degrade the peptide and are usually avoided. The molecule is hygroscopic in its solid form, so containers should remain sealed with desiccant. Solutions are less stable than powders and are generally prepared fresh. Light exposure is limited because aromatic residues can undergo photo-oxidation.
Semaglutide dissolves readily in water and in aqueous buffers near neutral pH. Solubility decreases near the isoelectric point, where net charge is minimal. Common laboratory solvents include phosphate-buffered saline and dilute ammonium bicarbonate. Strongly acidic or basic conditions may accelerate hydrolysis. Working concentrations are usually prepared by diluting a concentrated stock. Vial surfaces can adsorb small amounts of peptide at low concentrations, so carrier proteins or low-binding tubes are sometimes used.
Large randomised trials in adults with type 2 diabetes and in adults with obesity have reported reductions in body weight and improvements in several cardiovascular risk markers. One outcome trial found a lower incidence of major adverse cardiovascular events in participants with diabetes and established cardiovascular disease. Gastrointestinal effects such as nausea and vomiting are the most frequently reported adverse events and often diminish over time. Changes in lean body mass during weight loss are an area of ongoing investigation. Effects in adolescents and in pregnancy are less well characterised, and current labelling advises against use during pregnancy.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released after nutrient intake. The molecule contains 31 amino acid residues and differs from the native sequence at several positions. A non-natural residue at position eight resists the enzyme that normally truncates the hormone, while a lysine-linked fatty diacid side chain promotes binding to serum albumin. These two modifications extend the circulating half-life from minutes to roughly one week. The peptide is produced by solid-phase synthesis followed by selective acylation, and its identity and purity are confirmed by spectrometric and chromatographic techniques.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
Receptor activation raises intracellular cyclic AMP through Gs coupling, which promotes glucose-dependent insulin release and suppresses glucagon secretion when blood glucose is elevated. Effects outside the pancreas include slower gastric emptying and altered appetite signalling in the hypothalamus and hindbrain. The relative contribution of each tissue to overall metabolic outcomes remains an area of active investigation. Central mechanisms in particular are inferred mainly from animal models and indirect human measures rather than direct observation.
Serum protein binding dominates the pharmacokinetic profile. The attached chain associates strongly with albumin, shielding the peptide from enzymatic attack and slowing filtration by the kidney. This interaction extends the circulation half-life to roughly one week in humans, which supports weekly administration intervals. An oral version pairs the peptide with an absorption enhancer that transiently alters gastric epithelium, permitting limited uptake; bioavailability by that route is substantially lower than by injection.
Semaglutide belongs to the glucagon-like peptide-1 receptor agonist class, a group of synthetic peptides that imitate an incretin hormone released by intestinal L cells after food intake. Native GLP-1 circulates for only a few minutes because dipeptidyl peptidase-4 cleaves it rapidly. The hormone acts on pancreatic islets, the gastrointestinal tract, and several brain regions. Because the natural peptide is short-lived, development work concentrated on analogues that keep receptor activity while resisting enzymatic breakdown and renal clearance.
Carbon dioxide can be used to extinguish flames by flooding the environment around the flame with the gas. It does not itself react to extinguish the flame, but starves the flame of oxygen by displacing it. Some fire extinguishers, especially those designed for electrical fires, contain liquid carbon dioxide under pressure. Carbon dioxide extinguishers work well on small flammable liquid and electrical fires, but not on ordinary combustible fires, because they do not cool the burning substances significantly, and when the carbon dioxide disperses, they can catch fire upon exposure to atmospheric oxygen. They are mainly used in server rooms. Carbon dioxide has also been widely used as an extinguishing agent in fixed fire-protection systems for local application of specific hazards and total flooding of a protected space. International Maritime Organization standards recognize carbon dioxide systems for fire protection of ship holds and engine rooms. Carbon dioxide-based fire-protection systems have been linked to several deaths, because it can cause suffocation in sufficiently high concentrations. A review of CO2 systems identified 51 incidents between 1975 and the date of the report (2000), causing 72 deaths and 145 injuries.
21CFR50.3: Code of Federal Regulations, Title 21--Food and Drugs, Chapter I--Food and Drug Administration, Department of Health and Human Services, Part 50--Protection of Human Subjects, Subpart A--General Provisions, Sec. 50.3 Definitions 21CFR312.3: Code of Federal Regulations, Title 21--Food and Drugs, Chapter I--Food and Drug Administration, Department of Health and Human Services, Part 312--Investigational New Drug Application, Subpart A--General Provisions, Sec. 312.3 Definitions and Interpretations, archived from the original on June 26, 2003 ICH E6: Guidance for Industry - E6 Good Clinical Practice: Consolidated Guidance (PDF), U.S. Department of Health and Human Services, Food and Drug Administration, April 1996, archived from the original (PDF) on July 9, 2009 ICH E9: Guidance for Industry - E9 Statistical Principles for Clinical Trials (PDF), U.S. Department of Health and Human Services, Food and Drug Administration, September 1998, archived from the original (PDF) on July 10, 2009 NCI: Dictionary of Cancer Terms, National Cancer Institute, archived from the original on 2008-10-25, retrieved 2008-10-05 NLM: Glossary of Clinical Trials Terms, U.S. National Library of Medicine, archived from the original on 2011-09-02, retrieved 2008-10-05
=== Brady === In February 2019, the trial of Mikel Brady was scheduled for October 7, 2019, making Brady the first of the four set to stand trial for the 2017 prison attack. On October 21, 2019, Brady was found guilty of all four counts of first degree murder and ten other lesser charges, including attempted escape, assault with a deadly weapon and arson. The offence of first degree murder carries a sentence of either life imprisonment without the possibility of parole or the death penalty under North Carolina state law. During the sentencing trial, the defence argued for Brady to be sentenced to life imprisonment, citing the details of Brady's troubled childhood and past medical history of his psychiatric conditions. Brady's lawyer, Thomas Manning, summarized Brady's childhood into a poem, "As the twig is bent, so goes the tree". On the other hand, the prosecution sought the death penalty, with District Attorney Andrew Womble citing the brutality of the attack and aggravating factors in the case. Womble also quoted that if the jury settled on life imprisonment, "it will be open season on corrections officers in this state." On October 28, 2019, 30-year-old Mikel Brady was sentenced to death upon the jury's unanimous recommendation for capital punishment, making Brady the 143rd inmate to be condemned to death row in North Carolina; a total of 142 inmates were held on death row in North Carolina at the time of Brady's sentencing. After he was sentenced to death, Brady was at first held on death row at the Central Prison in Raleigh, North Carolina.
== Further reading == Maheshwari, Saurabh; Ingole, Dilip; Chatterjee, Samar; Rajesh, Uddandam; Anand, Varun (2021). "A case report of achondrogenesis type II (Langer-Saldino achondrogenesis)". Egyptian Journal of Radiology and Nuclear Medicine. 52 (1) 113. doi:10.1186/s43055-021-00479-0. ISSN 2090-4762. Kobayashi, Yukari; Ito, Yuki; Taniguchi, Kosuke; Harada, Kana; Yamamura, Michihiro; Sato, Taisuke; Takahashi, Ken; Kawame, Hiroshi; Hata, Kenichiro; Samura, Osamu; Okamoto, Aikou (2022-11-15). "Novel missense COL2A1 variant in a fetus with achondrogenesis type II". Human Genome Variation. 9 (1). Springer Science and Business Media LLC: 40. doi:10.1038/s41439-022-00218-5. ISSN 2054-345X. PMC 9663423. PMID 36376277.
Vosilasarm, also known by the development codes RAD140 and EP0062 and by the black-market name Testolone or Testalone, is a selective androgen receptor modulator (SARM) which is under development for the treatment of hormone-sensitive breast cancer. It is specifically under development for the treatment of androgen receptor-positive, estrogen receptor-negative, HER2-negative advanced breast cancer. Vosilasarm was also previously under development for the treatment of sarcopenia (age-related muscle atrophy), osteoporosis, and weight loss due to cancer cachexia, but development for these indications was discontinued. The drug is taken by mouth. Side effects of vosilasarm may include vomiting, dehydration, constipation, decreased appetite, weight loss, changes in sex hormone levels, elevated liver enzymes, and liver toxicity. Vosilasarm is a nonsteroidal SARM, acting as an agonist of the androgen receptor (AR), the biological target of androgens and anabolic steroids like testosterone and dihydrotestosterone (DHT). However, it shows dissociation of effect between tissues in preclinical studies, with agonistic and anabolic effects in muscle, agonistic effects in breast, and partially agonistic or antagonistic effects in the prostate gland and seminal vesicles. Vosilasarm was developed in 2010 and was first described in the literature in 2011. It was originally developed by Radius Health and is now under development by Ellipses Pharma.
Sources: en.wikipedia.org
== See also == Alpha nuclide List of nuclides Table of nuclides Isotope geochemistry Radionuclide Mononuclidic element Monoisotopic element Stable isotope List of elements by stability of isotopes Big Bang nucleosynthesis
=== 2013 class action lawsuit === In 2013, a proposed class action lawsuit, Jennifer L Saavedra v. Eli Lilly and Company, was brought against Eli Lilly claiming that the Cymbalta label omitted important information about "brain zaps" and other symptoms upon cessation. Eli Lilly moved for dismissal per the "learned intermediary doctrine" as the doctors prescribing the drug were warned of the potential problems and are an intermediary medical judgment between Lilly and patients; in December 2013, Lilly's motion to dismiss was denied. In December 2014, class certification was denied. A second attempt at certification in 2015 also failed.
== Qualifying == Teams that were not members of either the Premier League or English Football League competed in the qualifying rounds to secure one of 32 available places in the first round. On 6 August 2022, in an extra preliminary round match against Fleet Town, Newport (IOW) teenager Finn Smith became the youngest ever FA Cup goalscorer, a day after his 16th birthday. The fourth and final qualifying round was played on the weekend beginning 15 October. The winners from the fourth qualifying round were Oldham Athletic, AFC Fylde, King's Lynn Town, York City, South Shields, Curzon Ashton, Wrexham, Solihull Moors, Gateshead, Chesterfield, Alvechurch, Buxton, Coalville Town, FC Halifax Town, Torquay United, Maidenhead United, Hereford, Taunton Town, Eastleigh, Woking, Dagenham & Redbridge, Ebbsfleet United, Chippenham Town, Weymouth, Oxford City, Bracknell Town, Needham Market, Chelmsford City, Boreham Wood, Merthyr Town, Farnborough and Barnet. Needham Market was the only club in this season's tournament appearing in the competition proper for the first time, although reconstituted sides Merthyr Town and Farnborough were featuring at this stage for the first time in their own right following the liquidation of Merthyr Tydfil FC (in 2010) and Farnborough Town (in 2007). Of the others, Weymouth had last appeared in the first round in 2007-08, Coalville Town had last done so in 2004–05, Bracknell Town had last done so in 2000-01 and Alvechurch had last done so in 1973-74.
In addition, inbred mouse strains are used in the overwhelming majority of studies, while the human population is heterogeneous, pointing to the importance of studies in interstrain hybrid, outbred, and nonlinear mice. An article in The Scientist notes, "The difficulties associated with using animal models for human disease result from the metabolic, anatomic, and cellular differences between humans and other creatures, but the problems go even deeper than that" including issues with the design and execution of the tests themselves. In addition, the caging of laboratory animals may render them irrelevant models of human health because these animals lack day-to-day variations in experiences, agency, and challenges that they can overcome. The impoverished environments inside small mouse cages can have deleterious influences on biomedical results, especially with respect to studies of mental health and of systems that depend upon healthy psychological states. For example, researchers have found that many mice in laboratories are obese from excess food and minimal exercise, which alters their physiology and drug metabolism. Many laboratory animals, including mice, are chronically stressed, which can also negatively affect research outcomes and the ability to accurately extrapolate findings to humans. Researchers have also noted that many studies involving mice are poorly designed, leading to questionable findings.
=== Weight loss === Excess body weight is thought to be an important cause of sleep apnea. People who are overweight have more tissues in the back of their throat which can restrict the airway, especially when sleeping. In weight loss studies of overweight individuals, those who lose weight show reduced apnea frequencies and improved apnoea–hypopnoea index (AHI). Weight loss effective enough to relieve obesity hypoventilation syndrome (OHS) must be 25–30% of body weight. For some obese people, it can be difficult to achieve and maintain this result without bariatric surgery.
Sources: en.wikipedia.org
=== Nerve supply === The lungs are supplied by nerves of the autonomic nervous system. Input from the parasympathetic nervous system occurs via the vagus nerve. When stimulated by acetylcholine, this causes constriction of the smooth muscle lining the bronchus and bronchioles, and increases the secretions from glands. The lungs also have a sympathetic tone from norepinephrine acting on the beta 2 adrenoceptors in the respiratory tract, which causes bronchodilation. The action of breathing takes place because of nerve signals sent by the respiratory center in the brainstem, along the phrenic nerve from the cervical plexus to the diaphragm.
=== Definition === The definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term "chymistry", in the view of noted scientist Robert Boyle in 1661, meant the subject of the material principles of mixed bodies. In 1663, the chemist Christopher Glaser described "chymistry" as a scientific art, by which one learns to dissolve bodies, and draw from them the different substances on their composition, and how to unite them again, and exalt them to a higher perfection. The 1730 definition of the word "chemistry", as used by Georg Ernst Stahl, meant the art of resolving mixed, compound, or aggregate bodies into their principles; and of composing such bodies from those principles. In 1837, Jean-Baptiste Dumas considered the word "chemistry" to refer to the science concerned with the laws and effects of molecular forces. This definition further evolved until, in 1947, it came to mean the science of substances: their structure, their properties, and the reactions that change them into other substances—a characterization accepted by Linus Pauling. More recently, in 1998, Professor Raymond Chang broadened the definition of "chemistry" to mean the study of matter and the changes it undergoes.
Xi has taken a harder line on security issues as well as foreign affairs, projecting a more nationalist and assertive China on the world stage. His political program calls for a China more united and confident of its own value system and political structure. Foreign analysts and observers have frequently said that Xi's main foreign policy objective is to restore China's position on the global stage as a great power. Xi advocates "baseline thinking" in China's foreign policy: setting explicit red lines that other countries must not cross. In the Chinese perspective, these tough stances on baseline issues reduce strategic uncertainty, preventing other nations from misjudging China's positions or underestimating China's resolve in asserting what it perceives to be in its national interest. Xi stated during the 20th CCP National Congress that he wanted to ensure China "leads the world in terms of composite national strength and international influence" by 2049.
== Definition == Next-generation sequencing uses the techniques of metagenomics to identify and characterize the genome of bacteria, fungi, parasites, and viruses without the need for a prior knowledge of a specific pathogen directly from clinical specimens. The capacity to detect all the potential pathogens in a sample makes metagenomic next generation sequencing a potent tool in the diagnosis of infectious disease especially when other more directed assays, such as PCR, fail.
==== Low sex hormone levels ==== Clinical studies have consistently associated medical and recreational opioid use with hypogonadism (low sex hormone levels) in different sexes. The effect is dose-dependent. Most studies suggest that the majority (perhaps as much as 90%) of chronic opioid users develop hypogonadism. A 2015 systematic review and meta-analysis found that opioid therapy suppressed testosterone levels in men by about 165 ng/dL (5.7 nmol/L) on average, which was a reduction in testosterone level of almost 50%. Conversely, opioid therapy did not significantly affect testosterone levels in women. However, opioids can also interfere with menstruation in women by limiting the production of luteinizing hormone (LH). Opioid-induced hypogonadism likely causes the strong association of opioid use with osteoporosis and bone fracture, due to deficiency in estradiol. It also may increase pain and thereby interfere with the intended clinical effect of opioid treatment. Opioid-induced hypogonadism is likely caused by their agonism of opioid receptors in the hypothalamus and the pituitary gland. One study found that the depressed testosterone levels of heroin addicts returned to normal within one month of abstinence, suggesting that the effect is readily reversible and is not permanent. As of 2013, the effect of low-dose or acute opioid use on the endocrine system is unclear. Long-term use of opioids can affect the other hormonal systems as well.
Sources: en.wikipedia.org
差别集中在三处：第 8 位残基被非天然氨基酸取代，第 34 位换成精氨酸，第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率，侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。
胰岛素释放需要细胞内环腺苷酸与钙信号升高，同时依赖葡萄糖代谢产生的协同信号。血糖水平较低时协同信号不足，分泌增强有限。这一机制在降糖效果与低血糖风险之间提供了缓冲。
白蛋白结合是主要原因，它减少肾小球滤过并保护分子免受蛋白酶降解。序列修饰带来的酶解抵抗同样不可忽略，二者共同作用。脂肪链的疏水性还会影响组织分布，但其对总半衰期的贡献程度仍在研究之中。
It is a modified version of the natural hormone, with three amino acid changes and a fatty acid side chain added. These edits extend its half-life from minutes to about one week. The core receptor activity is retained.