If you have been reading about receptor agonist 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.
Last reviewed on 2025-07-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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.
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.
| 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 |
Pharmacological activity arises from agonism at the glucagon-like peptide-1 receptor, a G protein-coupled receptor expressed in the pancreas, the gastrointestinal tract, and the brainstem. Receptor activation raises intracellular cyclic adenosine monophosphate and enhances insulin release in a glucose-dependent manner, an effect that diminishes when blood glucose concentration is low. Other effects include slowed gastric emptying and hypothalamic satiety signalling. These pathways are described well. Receptor desensitisation rates across tissues, relative to the endogenous hormone, are still under investigation, and reported findings differ between laboratories.
The company that developed the compound filed it as a long-acting analogue, and it gained first approval in 2017 for type 2 diabetes. Later authorisations from several regulators extended the indication to chronic weight management, and the World Health Organization added the glucagon-like peptide-1 receptor agonist drug class to its model list of essential medicines in 2023. Production uses solid-phase peptide synthesis followed by side-chain conjugation and chromatographic purification. Supply constraints and cost differences across regions are well documented. Literature on long-term outcomes continues to grow, with many trials reporting surrogate endpoints rather than hard clinical endpoints.
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.
During the George W. Bush administration, relations between India and the United States blossomed, primarily over common concerns regarding growing Islamic extremism, energy security, and climate change. George W. Bush commented, "India is a great example of democracy. It is very devout, has diverse religious heads, but everyone is comfortable about their religion. The world needs India". Journalist Fareed Zakaria, in his book The Post-American World, described Bush as "being the most pro-Indian president in American history." Similar sentiments are echoed by Rejaul Karim Laskar, a scholar of Indian foreign policy and ideologue of Indian National Congress – the largest constituent of the United Progressive Alliance (UPA). According to Laskar, the UPA rule has seen a "transformation in bilateral ties with the US", as a result of which the relations now covers "a wide range of issues, including high technology, space, education, agriculture, trade, clean energy, counter-terrorism, etc". After the December 2004 tsunami, the US and Indian navies cooperated in search and rescue operations and in the reconstruction of affected areas. Since 2004, Washington and New Delhi have been pursuing a "strategic partnership" that is based on shared values and generally convergent geopolitical interests. Numerous economic, security, and global initiatives, including plans for civilian nuclear cooperation, are underway. First launched in 2005, cooperation on nuclear weapons reversed three decades of American non-proliferation policy.
== Prevention == Screening individuals for certain predisposing gene variants before initiating treatment with particular SJS-, TEN/SJS-, or TEN-inducing drugs is recommended or under study. These recommendations are typically limited to specific populations that show a significant chance of having the indicated gene variant since screening of populations with extremely low incidences of expressing the variant is considered cost-ineffective. Individuals expressing the HLA allele associated with sensitivity to an indicated drug should not be treated with the drug. These recommendations include the following. Before treatment with carbamazepine, the Taiwan and USA Food and Drug Administrations recommend screening for HLA-B*15:02 in certain Asian groups. This has been implemented in Taiwan, Hong Kong, Singapore, and many medical centers in Thailand and mainland China. Before treatment with allopurinol, the American College of Rheumatology guidelines for managing gout recommend HLA-B*58:01 screening. This is provided in many medical centers in Taiwan, Hong Kong, Thailand, and mainland China. Before treatment with abacavir, the USA Food and Drug Administration recommends screening for HLA-B*57:01 in Caucasian populations. This screening is widely implemented. It has also been suggested that all individuals found to express this HLA serotype avoid treatment with abacovir. Current trials are underway in Taiwan to define the cost-effectiveness of avoiding phenytoin in SJS, SJS/TEN, and TEN for individuals expressing the CYP2C9*3 allele of CYP2C9.
=== Dependency === Adrenal suppression will begin to occur if prednisone is taken for longer than seven days. Eventually, this may cause the body to temporarily lose the ability to manufacture natural corticosteroids (especially cortisol), which results in dependence on prednisone. For this reason, prednisone should not be abruptly stopped if taken for more than seven days; instead, the dosage should be gradually reduced. This weaning process may be over a few days if the course of prednisone is short but may take weeks or months if the patient had been on long-term treatment. Abrupt withdrawal may lead to an Addisonian crisis. For those on chronic therapy, alternate-day dosing may preserve adrenal function and thereby reduce side effects. Glucocorticoids act to inhibit feedback of both the hypothalamus, decreasing corticotropin-releasing hormone (CRH), and corticotrophs in the anterior pituitary gland, decreasing the amount of adrenocorticotropic hormone (ACTH). For this reason, glucocorticoid analogue drugs such as prednisone down-regulate the natural synthesis of glucocorticoids. This mechanism leads to dependence in a short time and can be dangerous if medications are withdrawn too quickly. The body must have time to begin synthesis of CRH and ACTH and for the adrenal glands to begin functioning normally again. Prednisone may start to result in the suppression of the hypothalamic–pituitary–adrenal (HPA) axis if used at doses 7–10 mg or higher for several weeks. This is approximately equal to the amount of endogenous cortisol produced by the body every day.
Sources: en.wikipedia.org
=== Thyroid disease === Fetal maternal microchimerism may be related to autoimmune thyroid diseases. There have been reports of fetal cells in the lining of the blood and thyroid glands of patients with autoimmune thyroid disease. These cells could become activated after delivery of the baby after immune suppression in the mother is lost, suggesting a role of fetal cells in the pathogenesis of such diseases. Two types of thyroid disease, Hashimoto's thyroiditis (HT) and Graves' disease (GD), show similarities to graft vs host disease which occurs after hematopoietic stem cell transplants. Fetal cells colonize maternal tissues like the thyroid gland and are able to survive many years postpartum. These fetal microchimeric cells in the thyroid show up in the blood of women affected by thyroid diseases.
=== Midlands Black Rhino Conservancy === The Mid West Rhinos maintain close links with the Midlands Black Rhino Conservancy. The conservancy is made up of several adjoining farms that give free rein to a number of the severely endangered Black Rhino. Each year the Mid West Rhinos stage the Midlands Black Rhino Conservancy T20 tournament. The tournament has grown from humble beginnings and now boasts participating teams from South Africa and Zambia. The proceeds from the tournament and other fundraising activities go directly to the conservancy.
The obliquity (axial tilt) of some airless planetary bodies in the Solar System, such as Mercury, the Moon,and Ceres, is very close to zero. Harold Urey first noted that depressions or craters located near the poles of these bodies would cast persistent shadows that can survive for geologic time periods (millions–billions of years). The absence of an atmosphere prevents mixing by convection, rendering these shadows extremely cold. If molecules of volatiles such as water ice travel into these permanent shadows, they become trapped for geologic time periods.
Several such models for mineral-mediated polymerization have emerged, such as the interlayers of layered double hydroxides like green rust over wet-dry cycles. Some scenarios for peptide formation have been proposed that are even compatible with aqueous solutions, such as the hydrophobic air-water interface and a novel "sulfide-mediated α-aminonitrile ligation" scheme, where amino acid precursors come together to form peptides. Polymerization of life's building blocks is an active area of research in prebiotic chemistry.
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。
Filtering removes particulate matter that can block columns or scatter light. A 0.22 micrometre membrane is typical, and the filter material should be checked for peptide adsorption.