If you have been reading about glucose-dependent 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 2025-09-05. Numbers and descriptions here follow the published literature rather than marketing material.
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。
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
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.
| 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 |
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.
Lyophilized semaglutide powder is typically held at minus twenty degrees Celsius for long-term storage. At that temperature, solid-state degradation reactions proceed slowly and the peptide remains intact for extended periods. Repeated freeze-thaw cycles are best avoided because they promote aggregation and can shift the proportion of monomeric peptide present. Working aliquots are often prepared so that each portion is thawed only once, and desiccant is placed inside the vial to limit moisture uptake.
Identity and purity are usually assessed by reverse-phase high-performance liquid chromatography coupled to mass spectrometry. Retention time and observed mass are compared against a reference standard run under identical conditions. Impurity profiles reveal deamidation products, oxidized methionine variants, and truncated fragments that arise during synthesis or storage. Peptide mapping through enzymatic digestion confirms the primary sequence, while amino acid analysis offers an independent check on overall composition.
Stability studies examine how temperature, pH, and moisture influence degradation rates over time. In aqueous solution, hydrolysis and deamidation accelerate as pH moves away from mildly acidic conditions. Light exposure and residual metal ions can also trigger oxidation of susceptible residues. Accelerated aging at elevated temperature is used to estimate shelf life, though extrapolation to room temperature carries uncertainty because individual degradation pathways do not always scale predictably.
Activation of the GLP-1 receptor couples to Gs signalling and raises intracellular cyclic AMP in pancreatic beta cells. The resulting insulin release depends on prevailing glucose concentrations, so the effect is greater when glucose is elevated. Receptor engagement also suppresses glucagon secretion and slows gastric emptying, which flattens post-meal glucose excursions. In the central nervous system, signalling in hypothalamic and brainstem regions is associated with reduced appetite and lower energy intake. Studies continue to examine effects on cardiac, renal and hepatic endpoints; whether those benefits are independent of weight change remains an open question.
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.
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.
==== Metabolism and elimination ==== Hepatic – the primary metabolite is 4-carboxypyrazole (about 80 to 85% of an administered dose). Other metabolites include the pyrazoles 4-hydroxymethylpyrazole and the N -glucuronide conjugates of 4-carboxypyrazole and 4-hydroxymethylpyrazole. Following multiple doses, fomepizole rapidly induces its own metabolism via the cytochrome P450 mixed-function oxidase system. In healthy volunteers, 1.0 to 3.5% of an administered dose was excreted unchanged in the urine. The metabolites also are excreted unchanged in the urine. Fomepizole is dialyzable.
== Trade names == Several companies have attempted to trademark particular strains, and as a marketing technique, have invented scientific-sounding names for the strains. Danone (Dannon in the United States) markets the subspecies strain DN 173 010 as Bifidus Digestivum (UK), Bifidus Regularis (US and Mexico), Bifidobacterium Lactis or B.L. Regularis (Canada), DanRegularis (Brazil), Bifidus Actiregularis (Argentina, Austria, Belgium, Bulgaria, Chile, Czech Republic, France, Germany, Greece, Hungary, Israel, Italy, Kazakhstan, Netherlands, Portugal, Romania, Russia, South Africa, Spain and the UK), and Bifidus Essensis in the Middle East (and formerly in Hungary, Bulgaria, Romania and The Netherlands) through Activia from Safi Danone KSA. One notable example involved Danone’s attempt to enforce a trademark on an invented probiotic strain name. Danone held a trademark for “Bifidus Essensis”, which it used in marketing its Activia products, and sued Glanbia after the launch of Yoplait “Essence” products in the Irish market, claiming trademark infringement. In 2007, the Irish Commercial Court ruled against Danone, finding that the “Essensis” trademark had not been genuinely used as a product brand in the relevant market and ordering its revocation in that context. Chr. Hansen A/S from Denmark has a similar claim on a strain of Bifidobacterium animalis subsp. lactis, marketed under the trademark BB-12. Lidl lists "Bifidobacterium BB-12" in its "Proviact" yogurt. Bifidobacterium lactis Bl-04 and Bi-07 are strains from DuPont's Danisco FloraFIT range.
=== Mixtures === Typically, supercritical fluids are completely miscible with each other, so that a binary mixture forms a single gaseous phase if the critical point of the mixture is exceeded. However, exceptions are known in systems where one component is much more volatile than the other, which in some cases form two immiscible gas phases at high pressure and temperatures above the component critical points. This behavior has been found in systems such as N2-NH3, NH3-CH4, SO2-N2 and n-butane-H2O.. The systems composed by a supercritical fluid and a liquid are named Gas expanded liquids. The critical point of a binary mixture can be estimated as the arithmetic mean of the critical temperatures and pressures of the two components,
Some research has been carried out to improve the efficacy of commercial incandescent lamps. In 2007, General Electric announced a high efficiency incandescent (HEI) lamp project, which they claimed would ultimately be as much as four times more efficient than current incandescents, although their initial production goal was to be approximately twice as efficient. The HEI program was terminated in 2008 due to slow progress. US Department of Energy research at Sandia National Laboratories initially indicated the potential for dramatically improved efficiency from a photonic lattice filament. However, later work indicated that initially promising results were in error. Prompted by legislation in various countries mandating increased bulb efficiency, hybrid incandescent bulbs have been introduced by Philips. The Halogena Energy Saver incandescents can produce about 23 lm/W; about 30 percent more efficient than traditional incandescents, by using a reflective capsule to reflect formerly wasted infrared radiation back to the filament, from which some is re-emitted as visible light. This concept was pioneered by Duro-Test in 1980 with a commercial product that produced 29.8 lm/W. More advanced reflectors based on interference filters or photonic crystals can theoretically result in higher efficiency, up to a limit of about 270 lm/W (40% of the maximum efficacy possible). Laboratory proof-of-concept experiments have produced as much as 45 lm/W, approaching the efficacy of compact fluorescent bulbs which is still lower than LED bulbs.
Sources: en.wikipedia.org
Psychedelic drug use can cause hallucinogen-induced psychotic disorder (HIPD). HIPD is a form of substance-induced psychosis. The symptoms of HIPD are psychosis with paranoia, delusions, hallucinations, disorganized thinking, disorganized behavior, or insomnia that continue after the effects of the drug. Individuals with a personal or family history of mental illness are at the highest risk for hallucinogen-induced psychotic disorder. HIPD due to psychedelics is most commonly associated with LSD, but can be caused by DMT, mescaline, and psilocybin as well. Hallucinogen-induced psychotic disorder is a medical emergency. Without treatment, the psychosis can persist for weeks or months. An atypical antipsychotic medication such as aripiprazole, quetiapine, olanzapine, or risperidone is used to treat HIPD. Psilocybin-induced states of mind share features with states experienced in psychosis and researchers have called for investigation of the relationship. Hallucinogen-induced psychotic disorder has been reported with psychedelics in small percentages of individuals, and the rates appear to be higher in people with schizophrenia. The rate of hallucinogen-induced psychotic disorder is 0.6% in randomized controlled trials that exclude individuals with bipolar disorder or schizophrenia. In studies that included individuals with schizophrenia, 3.8% developed hallucinogen-induced psychotic disorder.
biotechnology company specialized in the early discovery and development of recombinant polyclonal antibodies, after having acquired a significant stake in 2017. In 2022, Grifols acquired Biotest, a German manufacturer and provider of plasma-derived medicines.
No cases of IGFBP3 gene deletion in humans have been reported, but mice lacking the gene show near-normal growth. IGFBP-3 exerts antiproliferative effects in many cell types by blocking the ability of IGF-1 and IGF-2 to activate the IGF1R (which stimulates cell proliferation). For example, in esophageal epithelial cells, responsiveness to IGF-1 stimulation is suppressed by secreted IGFBP-3 and restored when IGFBP-3 is downregulated by epidermal growth factor. IGFBP-3 can also inhibit cell function by mechanisms that are independent of effects on IGF1R signaling, even in cells that entirely lack IGF1R. IGF (or IGF1R) independent effects are commonly studied using mutant forms of IGFBP-3 with decreased IGF binding affinity. Thus, IGFBP-3-induced apoptosis in differentiating chondrocyte precursor cells is seen equally with a non-IGF binding IGFBP-3 mutant, demonstrating that the mechanism does not involve IGF binding. IGF1R-independent growth inhibition by IGFBP-3 may involve the induction of pro-apoptotic proteins such as Bax and Bad and may be mediated by ceramides (pro-apoptotic lipids), or potentiate ceramide action IGFBP-3 interaction with nuclear hormone receptors may also lead to inhibition of cell proliferation. Contrasting with the typical growth-inhibitory effects of IGFBP-3, stimulation of cell proliferation by IGFBP-3 has also been observed. This can occur either by enhancing IGF-stimulated proliferation or in the absence of IGF-1.
Sources: en.wikipedia.org
==== Trade policy ==== In February 2005, Sanders introduced a bill that would have withdrawn the permanent normal trade relations (PNTR) status that had been extended to China in October 2000. He said to the House, "Anyone who takes an objective look at our trade policy with China must conclude that it is an absolute failure and needs to be fundamentally overhauled", citing the American jobs being lost to overseas competitors. His bill received 71 co-sponsors but was not sent to the floor for a vote.
== Contraindications == Gepirone is contraindicated in people that have experienced an allergic reaction to gepirone, a corrected QT interval > 450 msec, a history of congenital long QT syndrome, use medications that strongly inhibit CYP3A4 (an enzyme involved in gepirone's metabolism), severe liver problems, or have used a monoamine oxidase inhibitor (MAOI) medication within 14 days.
=== Duration and exclusivity === Numerous health organizations, including, but not limited to, the CDC, WHO, National Health Service, Canadian Pediatric Society, American Academy of Pediatrics, and American Academy of Family Physicians, recommend breastfeeding exclusively for six months following birth, unless medically contraindicated. Exclusive breastfeeding is defined as "an infant's consumption of human milk with no supplementation of any type (no water, no juice, no nonhuman milk and no foods) except for vitamins, minerals and medications." Supplementation with human donor breastmilk may be indicated in some specific cases, as discussed below. After solids are introduced at around six months of age, continued breastfeeding is recommended. The American Academy of Pediatrics recommends that babies be breastfed at least until 12 months, or longer if both the mother and child wish. The World Health Organization's guidelines recommend "continue[d] frequent, on-demand breastfeeding until two years of age or beyond. The American Academy of Pediatrics policy statement also supports continued breastfeeding to 2 years and older, depending on the mother and child. Extended breastfeeding means breastfeeding after the age of 12 or 24 months, depending on the source. In Western countries such as the United States, Canada, and Great Britain, extended breastfeeding is relatively uncommon and can provoke criticism. Globally exclusive breastfeeding rose from 37.0% to 47.4% between 2012 and 2024;.
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。
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and cleared quickly. Semaglutide carries a position 8 substitution that blocks that cleavage and a fatty diacid chain that binds albumin. Together these changes extend its circulating half-life to about one week.